Axle swap help 4 Noobie

[CharliesHeep73]

Maybe it’s time for me to do a build thread .


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[tgreese]

Jeep never sold the T-15 with the 401. And that's a CJ T-15, too short for a V8 Wagoneer. Transfer case shifter is '72-73ish CJ. That shifter stalk will come up under your dash.

The '72-75 304 CJ5, CJ-6 and '72-73 Commando got the T-15 with the 304. A 401 swap was really easy in a 304 CJ or Commando; you need the 401 flywheel though.

There were some 401 T-18 Wagoners or J-trucks in 1974, but none after that. You could get the 4V 360 with the T-18 after that. V8 T-15 trucks got the 2V 360 typically, or maybe the 304 '71-73? The FSJ V8 manual transmissions are distinctive, with a very long input shaft and a 5" thick adapter between the bell and transmission. Hard to miss.

[CharliesHeep73]

I picked up the whole set up pretty cheap. But your info definitely explains why I didn’t find any info of the t15 on a 401. Everything I did see was a t18.. Before I made the 2 1/2 hour drive to pick up the motor this Saturday I had the guy confirm with a picture that the block was in fact stamped 401.

What’s your thoughts on mating up the 401 with my TH400? Or should I just go by the saying “keep it simple stupid” and go with a 360.

My block that I currently have isn’t the original 360 on the 73 Wagoneer Its stamped 5.9 and it definitely needs to get rebuilt… since it’s been sitting way too long. So I started looking for a block stamped 360 instead to rebuild. But I found this setup pretty cheap and I couldn’t pass it up.


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[CharliesHeep73]

I’m not going to lie though… the thought of a manual transmission was really catching my attention.. but automatic it is


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[tgreese]

If I were thinking of putting the 401 in to a '73, I would consider two things (there may be others - but none come immediately to mind). First, the 401s sometimes don't suffer rebuilding well. The 401 bore is close to the absolute maximum for that block, and the cylinder walls are comparatively thin. Some of them overheat after boring oversize, some don't. Thin walls -> hot spots. I presume it depends on how well centered the core was when the block was cast. Plenty of info about this in old posts.

The other is availability of a 401 flexplate for your transmission. It probably does not exist. Prior to 1974ish, Jeep used the "nailhead" or "universal" TH400 with a ring adapter. I don't think that flexplate interchanges with the '74-ish and later transmissions with the purpose-built AMC case. Your machine shop could take your 360 flexplate and balance it to the 401, so it's not impossible. Or switch to the later AMC case transmission.