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Hi. I'm trying to convert my 1979 J10 4x4 from 4 speed stick to a 1987 Wagoneer automatic. I have a local junkyard that has a 1987 wagoneer auto 4x4. I am getting the tranny, steering column/shifter, torque converter, 2WD/4WD switch below the dash and the floor mounted hi-lo lever. Anyone know what else I need? Trans mount(s)? Crossmember? Xfer case? Is there a Brain between the 2WD/4WD switch and the trans? Harness? Any help would be appreciated. He'll get me whatever I ask for this time but If i have to ask for more parts later it will get very expensive. Thanks!

There are a lot of differences between a '79 and earlier vs. '80 and later. In 1980, Jeep switched from GM automatics to Chrysler, from Borg-Warner or Dana transfer cases to New Process, and moved the front differential and driveshaft to the driver's side. The '88 stuff won't work with your front axle. The Wagoneer front axle is too narrow for a J-truck and almost certainly has the wrong gear ratio. Your transfer case will not work with that transmission without an expensive adapter (more than $500) and taking the transmission completely apart to convert it. The Wagoneer transfer case drops on the wrong side for your front axle. These vehicles got a major redesign for 1980. I suggest you're better off to look for a J-truck with an automatic rather than convert what you have. Pass the 4-speed truck along to someone that will appreciate it - there are a lot more of these vehicles with automatics than 4-speeds.

That is all bad news, but I appreciate the speedy and thorough reply and advice just the same. Thanks!

tgreese wrote: ↑Thu Mar 11, 2021 11:06 am The Wagoneer front axle is too narrow for a J-truck and almost certainly has the wrong gear ratio.

Would a 1979 and earlier Wagoneer transmission work? Or am I limited to J-Truck only?

Does not get a lot easier going earlier.

'79 or earlier Wagoneer or J-truck will have the same transmission and transfer case within the same years mostly. Very nearly all of the '74-79s will have a GM TH400 with the AMC case, and the Quadratrac (Borg-Warner 1339) full-time transfer case. The Quadratrac has its own story to tell, which you should research before you commit. In terms of compatibility with your truck, there is no problem, but some love the Quadratrac and some hate them. Certainly it was a major advance in its time, and works very well when in good condition, but there can be reasons to avoid them. Only the Quadratrac will work with these transmissions, unless you buy a different expensive adapter and take the transmission completely apart to swap over to your transfer case.

Going earlier, some '73s used the "universal" TH400 with your transfer case and an engine adapter that will work with your engine. '71-72 had the AMC V8 and the same transfer case, but the engine crankshaft design was different and the engine adapter pieces won't fit.

Again, I'd suggest that you look for a different '80-up J-truck if you want one with an automatic. '79-down will have automatics too, but most will be Quadratrac, which may be ok for you once you look into it.

tgreese wrote: ↑Thu Mar 11, 2021 12:42 pm Does not get a lot easier going earlier.

'79 or earlier Wagoneer or J-truck will have the same transmission and transfer case within the same years mostly. Very nearly all of the '74-79s will have a GM TH400 with the AMC case, and the Quadratrac (Borg-Warner 1339) full-time transfer case.

TGREESE,
Again, thank you for your quick reply and awesome info. So I will definitely consider a complete truck swap. But if I understand right, if I stick 74-79 Wago or J10 4x4, I will be able to swap 4-speed 4x4 to auto 4x4 by swapping transmission, steering column, shifter linkage from column to tranny, pedal assembly? Would I need anything else off the donor?
Transfer case?
Crossmember?
Speedo Cable?
Other?

'74-79 is a TH400 and almost certainly a Quadratrac transfer case.

You cannot use any other transfer case with this transmission without replacing its unique long tail shaft. The tail shaft is the last thing to come out when you disassemble these transmissions. The new tail shaft is part of an adapter kit to a different transfer case, ca $500.

Your guess is as good as mine regarding what else you would need. Ideally you'd get the whole donor, and take what you need.

tgreese wrote: ↑Thu Mar 11, 2021 1:09 pm '74-79 is a TH400 and almost certainly a Quadratrac transfer case.

Thanks. I was asking if my 1979 J10 4x4 with a 4 Speed manual has the same transfer case (Quadratrac) in it already or if I would be required to get the transfer case from the automatic donor as well.

You can also use a floor shifter with the auto.

As tgreese mentions, you have to pull the transmission (TH400) apart in order to change out the output shaft to work with a D20, as well as buying the adapter. OEM adapters were very brittle and often cracked, and were only available for a few years. 74-79 was Quadra-Trac only behind automatics.

Also you have to change the pilot bushing out on the back of the crank. Both front and rear drive shafts will have to be replaced (may be able to just shorten one of them). The cross member will most likely have to be moved into the other set of holes. You will have to vacuum for the vacuum modulator on the TH400.

If you do go forward with this, there may be somebody wanting all the manual parts, so don't toss them. The 4sp manuals are more desirable in many cases.

Out of curiosity, why are you wanting to switch it?

SRT6 wrote: ↑Thu Mar 11, 2021 1:33 pm

tgreese wrote: ↑Thu Mar 11, 2021 1:09 pm '74-79 is a TH400 and almost certainly a Quadratrac transfer case.

Thanks. I was asking if my 1979 J10 4x4 with a 4 Speed manual has the same transfer case (Quadratrac) in it already or if I would be required to get the transfer case from the automatic donor as well.

A Quadratrac is not compatible with a manual transmission - it cannot withstand the impact load. All manual transmissions in 1979 got the Dana 20 geared transfer case. You would know this if you read the factory service manual, free to read and download here. https://oljeep.com/edge_parts_man.html

Stuka wrote: ↑Thu Mar 11, 2021 1:34 pm You can also use a floor shifter with the auto.

As tgreese mentions, you have to pull the transmission (TH400) apart in order to change out the output shaft to work with a D20, as well as buying the adapter. OEM adapters were very brittle and often cracked, and were only available for a few years. 74-79 was Quadra-Trac only behind automatics.

Also you have to change the pilot bushing out on the back of the crank. Both front and rear drive shafts will have to be replaced (may be able to just shorten one of them). The cross member will most likely have to be moved into the other set of holes. You will have to vacuum for the vacuum modulator on the TH400.

If you do go forward with this, there may be somebody wanting all the manual parts, so don't toss them. The 4sp manuals are more desirable in many cases.

Out of curiosity, why are you wanting to switch it?

Thanks! My wife found the truck and she can't drive stick and mainly want's it for easy, chill rides down to old town, etc. So you basically need everything between the front and rear axles, and everything up to the engine block, plus a new pilot bearing. OK. Why the new pilot bearing? Flywheel too? Sorry. I have done these swaps in both directions on many mustangs, miata's, etc with no drama.

SRT6 wrote: ↑Thu Mar 11, 2021 1:42 pm

Stuka wrote: ↑Thu Mar 11, 2021 1:34 pm You can also use a floor shifter with the auto.

As tgreese mentions, you have to pull the transmission (TH400) apart in order to change out the output shaft to work with a D20, as well as buying the adapter. OEM adapters were very brittle and often cracked, and were only available for a few years. 74-79 was Quadra-Trac only behind automatics.

Also you have to change the pilot bushing out on the back of the crank. Both front and rear drive shafts will have to be replaced (may be able to just shorten one of them). The cross member will most likely have to be moved into the other set of holes. You will have to vacuum for the vacuum modulator on the TH400.

If you do go forward with this, there may be somebody wanting all the manual parts, so don't toss them. The 4sp manuals are more desirable in many cases.

Out of curiosity, why are you wanting to switch it?

Thanks! My wife found the truck and she can't drive stick and mainly want's it for easy, chill rides down to old town, etc. So you basically need everything between the front and rear axles, and everything up to the engine block, plus a new pilot bearing. OK. Why the new pilot bearing? Flywheel too? Sorry. I have done these swaps in both directions on many mustangs, miata's, etc with no drama.

Oh yes, you need a flex plate for your engine (AMC's are externally balanced, and each displacement has its own balance). So if you have a 360, you need a flex plate for a 360. And as I recall, the automatics don't use a pilot bushing at all, the manual will. So it needs to be removed.

Thanks to all! If I end up going the conversion route i will post a required donor items list. But hopefully some one will just trade me their auto J-10!

The TH400 does not need a pilot bearing like a manual transmission, but it does need a thin bushing pressed into the crankshaft to support the front of the TH400 convertor. No personal experience with this, but you can search old posts here and at IFSJA.org ... I recall there is a source for the bushing, maybe Novak? Yep - https://www.novak-adapt.com/catalog/pil ... /j5352374/

SRT6 wrote: ↑Thu Mar 11, 2021 2:32 pm Thanks to all! If I end up going the conversion route i will post a required donor items list. But hopefully some one will just trade me their auto J-10!

Another path...
Get an '80-up Jeep 727 transmission and a Dodge/Chevy (np208 or np241) passenger drop transfer case.

Mmm. You may have driveshaft interference with a 727 and passenger drop in a Wagoneer. I have heard conflicting reports.

D300 and a 727 will definitely interfere. I think the front ouput on a 208 or 241 is offset enough to not cause any issues, as thats what Chrysler used in their 4wds for a few years before switching to driver drop.