1970 J2500 - Buick 350 - TH400

[Thunderspud]

Heyo! I decided I wanted yet another never-ending money sink this winter so I did the sensible thing and bought the most unsalvageable example of a J-truck I could find directly from the jaws of the crusher at the local salvage yard. $500, 20 minutes, and two extremely skilled excavator drivers later........we had a Jeep hanging by chains in mid-air to drive the trailer under. The only plan I have for it currently is to put it back on the road (mainly dirt) and go grab ice cream from the local creamery by the time spring rolls around.

As the title states.....this is what I think I have......most of a 1970 J2500 (minus what the rust gods took as a sacrifice), what appears to be a relatively stock Dauntless V8, a TH400, Dana 20 TC, and Dana 44s front and rear. The fronts are of the closed-knuckle variety, so I am making an assumption that they are original, or at least from the same vintage.

I wasn't sure where to introduce myself, and I suppose this post is more about getting that out of the way than anything else. I have plenty of questions for you guys, but until then here are a bunch of random pictures of the thing in an Imgur album so everyone can heckle me for my bad judgment...assuming I am not too new to post the link to it. I would add them here, but it seems like they are all way too large of a file size.

P.S. - If the album is visible....you may notice that the data tag and the door sticker say different things.....I sure did. My current assumption is that somebody stuck the data tag on later for some unknown reason. Feel free to educate me if you guys have a better explanation. I welcome the knowledge.

https://imgur.com/a/hKlmJWY

[sierrablue]

Welcome aboard! Looks like you caught the Jeep bug...specifically the FSJ variant...

About all I can tell you about the VIN is it looks like a relatively early one in production, which may or may not line up with it being built in January of 1970. Others on here will have a better idea and be able to tell you more I'm sure.

[tgreese]

Welcome from Boston. Your general location?

IFSJA has some VIN decoding information here: https://www.ifsja.org/tech/figures/index.html A quick look shows both 3408 J3000 4WD and a 2406 J2000 4WD are legitimate numbers. These are different wheelbases, so you should be able to reconcile with the truck.

You will notice that, in the Kaiser years, the VIN does not convey much information. VINs were assigned sequentially and continuously across the years. Not like the 'new models every year' VINs that Detroit (and later AMC) used for later Jeeps.

In most states, the VIN follows the frame. The VIN tag on the firewall is easy to transfer; doors can be changed too. There should be the sequential part of the VIN stamped into the top of the frame near the front passenger shock mount. This should match your VIN.

[Yeller]

Welcome aboard from a fellow 1970 J2500 owner

[devildog80]

Lots of love going into this one for sure. Will be following.
Congrats

[tgreese]

Also, first year for open knuckle in these trucks is 1974. If you have not purchased the TSM it is available on media for under $30 at RockAuto. You might also consider obtaining the 1972 TSM, similarly available. The TSM was redone by AMC after they took over, and there is more and better information there. The '72 model is basically the same as the '70 and '71 except for the adoption of the AMC V8s in place of the Buick.

[Thunderspud]

We are in the foothills of the national park in east Tennessee. Speaking on the VIN (and identification in general), luckily I am not all that worried about its provenance. Mainly just want to know what I have so I can plan for the mountain of parts I'm gonna have to throw at this thing to get it back under its own power in a timely manner. When I initially grabbed it from the scrap yard I hadn't even opened the hood, nor either door. Not because I didn't want to, but simply because they were all completely stuck closed. The passenger door still is, but that's probably best saved for another post. At the time I somehow convinced myself that was a good thing..... can't steal parts from an engine you can't access, after all.

I actually picked up a used manual (pictured below) before I even bought the truck. Mechanics notes and all. I had already decided I wanted a Buick-powered Jeep at that point.....for reasons. So I got a head start. Will keep an eye out for the newer manual as well.

s-l1600.jpg

s-l1600 (1).jpg

The main focus right now is just pulling the cab and bed, tearing things down to the frame, and making sure the major components in the drive train are salvageable. Based on what I intend to use this truck for (things like cruising the forest service roads and grabbing a burger in town every now and then) I am probably going to end up with a "best bang for your buck" approach to this whole thing. Gonna try to enjoy the journey more than the destination on this one.

One thing that I could use some knowledge about is whether or not any of the Jeep trucks of this vintage with the Buick 350 ever came with a Quadrajet. More specifically, did any of the Buick-equipped Jeeps of the era come with a 4 barrel intake? I suspect I have a seemingly unmolested Jeep spec Buick 350....with the exception of the intake and above. At least the casting/serial numbers I have been able to unearth so far seem to indicate as such.

[tgreese]

Regarding the Quadrajet, I don't think so. Nearly all these were 2V, except for a few "Super Wagoneers" (not J-trucks, but Wagoneers also came with the Buick). You could look at the '62-73 parts book here https://oljeep.com/edge_parts_man.html to check for certain. I find a Holley 4V there but no Quadrajet. In your picture, it looks like a 2V-4V adapter with whatever is on there.

(later) Looks like the 327 and the 360 could come with a 4V, not the 350. The 327 appears to be the Super Wagoneer, and the 360 got a Motorcraft across all FSJ models '71 on.

If I wanted a Quadrajet, I'd likely skip searching for an OEM iron manifold and buy a new aftermarket manifold. TA Performance has them. I'd paint it if I wanted it to look original.

I wondered about your location because of the oxidation distribution on your truck. Looks like a wet environment, and the windows were open a long time. Road salt will rust the rockers and bed more.

[Srdayflyer]

buick 350 , you have a lot of options the 70's 4bbl had 10:1 compression and if i remember around 325 hp and i think 300 torque, 2bbl had 9.0-1 or 9.25-1,buick blocks are high Nickel content , i rebuilt my 70GS and the machine shop said all they recommended was to de-ridge , and hone, didnt need a bore, but if i had the opportunity i slip in a torque monster 455 mill 425 hp 525 tq qt 2500 rpm
but TA performance will get you squared away on the buick mill, thats all they do is buicks.

[Srdayflyer]

1 other item on BOP (buick , olds, pontiac)the trans mission is totally different from a chevy th350/th400 trans bolt pattern and a chevy will not bolt up to a bop engine, just and important FYI

[Yeller]

The turbo 400 in the Jeeps behind the Buick is even more odd…. it used the old Cadillac/Buick Nail Head bolt pattern and has an adapter from that to the Buick. These were genuinely put together from whatever they could do on a low budget.

Here’s the adapter

[tgreese]

The turbo 400 in the Jeeps behind the Buick is even more odd…. it used the old Cadillac/Buick Nail Head bolt pattern and has an adapter from that to the Buick. These were genuinely put together from whatever they could do on a low budget.

Here’s the adapter

This is an interesting story, but something of a tangent from what the OP was asking.

Jeep adopted the Buick nailhead (and Cadillac?) aka "universal" case TH400 for all their automatic-equipped offerings starting in 1965. The nailhead buick blocks stick out toward the transmission bellhousing a couple of inches, making the nailhead case shorter overall than the case for other BOP engines or Chevrolets. This leaves room for an adapter between the block and transmission in other applications, as you see above.

The switch to TH400 coincided with the end of the 230 OHC engine, which was offered - in at least Wagoneers - with a Borg-Warner automatic and the single-speed Dana 21 transfer case. I kinda wonder if they used the nailhead transmissions because that's all that GM offered as a commodity component in that era. As I understand it, other manufacturers in the era such as Jaguar offered the TH400, and it was also the nailhead case transmission. Maybe there are other examples. Did Checker use the TH400 and was it a nailhead transmission?

Could be that Jeep stuck with the nailhead transmission to unify their automatic transmissions across all models, but they had both the 225 V6 and the 350 in '66 and '69 resp. Kinda seems like they could have used the Buick case TH400s if it were available. Indeed, it was 1974 before they used a bespoke TH400 for the AMC engines, relying on the nailhead transmission for automatic Jeep/AMC sixes and V8s until then.

Indeed, for passenger cars, AMC went from the Borg-Warner transmissions to Chrysler transmissions in '72 (?) and I suspect they would have converted Jeeps to Chrysler transmissions sooner if they would work with passenger drop. The bespoke AMC TH400s would never have existed. Or perhaps Chrysler was unwilling to build A727s with the long output shaft the nascent Quadratrac needed. Perhaps AMC did not have the capital to convert Jeeps to the Chrysler transmissions and upgrade to the Quadratrac at the same time. Just speculation.

BTW there are lots of BOP engines that you could swap in to replace the 350. Most popular have been the Buick big block engines, and the big Cadillacs (472, 500). The Cadillacs work well because they are a big step up from the 350, and are a compact engine compared to other GM offerings of similar displacement. I would hesitate to go ahead with a BB Pontiac or Oldsmobile if the starter was on the driver's side - might not work with the Jeep adapter even though they are both BOP engines.

I would mention - the parts specific to the adapted Jeep TH400s are unobtainium today, except for what you can find from wrecks or part-outs. The following Jeep engines used the adapted TH400: AMC 327, AMC 232 (the pre-71 "Rambler" engine in Wagoneers and J-trucks), Buick 225 and 350, AMC 232 (the post-70 version, which may exist with the TH400 in the Commando), AMC 258, AMC 304 (FSJs to '72, '72-73 Commando), AMC 360. If unique parts are broken or unavailable, it may be better to go to the Buick transmission for the 225 or 350. For the later AMC engines, the solution is the later bespoke TH400, for which parts are available. If you have a 327 or the Rambler 232, you''ll have to rely on junkyards. Note that convertors can be rebuilt - check the classic car specialists, maybe online or Hemmings).

[mud89]

Yep you have two different VINs :
- one for a '70 J2000 with a Buick engine
- one for a '71 J4000 with an AMC 360 engine
The cab and the powertrain seem to correspond to the J2000 VIN
Did you measure the bed length ?
Is it 7ft or 8ft ?