J20 Trans. Question

[kmj153]

I'm sorry if there is/was a write up answering this question but I just joined. My friend has a 1974 J20 with a manual transmission. I used the vin decoder to determine that it has a 401, etc. I just wanted to know if it has a T18 or T18A? It hasn't ran in a few years and he is not a Jeep guy so he doesn't know much about it. Just wondering if/how you can tell the difference without driving it.

[Kali]

According to the vin its a 401 and a manual tranny? Now thats something Ive only seen a couple of times. I think the J20 wouldn't have an option for anything but a T18. t-18/t-18a doesnt make a difference in the FSJs, they all had a granny 1st gear (6.32:1) and then 3 more street-usable gears.

[kmj153]

thanks for the quick response. You just made my day.

[joe]

I'm sorry if there is/was a write up answering this question but I just joined. My friend has a 1974 J20 with a manual transmission. I used the vin decoder to determine that it has a 401, etc. I just wanted to know if it has a T18 or T18A? It hasn't ran in a few years and he is not a Jeep guy so he doesn't know much about it. Just wondering if/how you can tell the difference without driving it.
If it's a 401/T18 it's rare. I have never seen or even heard of a 401 in a FSJ offered w/o the auto/QT package. But...a well respected member here (FSJeeper) has.
The AMC factory TSM's don't mention/list a 401/manual combo but....yeah another but...;)
The factory parts manual does list a flywheel p/n (not AT flexplate)... so it's possible a manual trans was a special order option?

Post up your VIN please. The 7th digit is the motor...Z=401, N or P ==360 and A == 258.
The 3rd digit is the trans: A=auto and m/n/o/p = 4speed.

[tgreese]

The dealership I worked at would sell new CJ-5s with a 401 if you wanted one, but they were dealer installed. It's possible that Jeep would let you special order a 401 with a T-18, since they were pretty cooperative about such things in that era.

Be sure your friend's truck actually has a 401 by looking at the cast-in numbers on the underside of the engine. It's possible this is really a 360/T-18 truck with a transplanted VIN plate. The engines look identical from above. If so, the VIN will have a Z code for a 401 and an A code for the automatic. A factory 401/T-18 VIN should have both a Z and an M for 401 and 4-speed.

[kmj153]

I wish I could post up some pictures, I am not sure how. Here is the vin: J4M462ZN79172

[trellis8]

N code 360 with a manual trans. z = 8000# gvw.

[kmj153]

yeah, sorry to get everyone's hopes up. I just double checked the vin myself, I was wrong.:o :banghead:

[joe]

I wish I could post up some pictures, I am not sure how. Here is the vin: J4M462ZN79172
OK I mislead you about the 7th digit of the VIN. It's the 8th digit that defines the motor...


This may help explain the somewhat mythical 401/4 speed. According to the VIN it's a 360 from the factory.


The VIN digits:
J=Jeep
4=1974
M=4 spd
46= J20
2= townside box
Z=8000 gvwr
N= "360 V8 w/2bbl carb"

Note the last line...I would crawl under the truck and look behind the motor mounts and see if 401 or 360 is cast into the block before paying for a "401 w/4spd"


edit: dayum I gotta learn to type faster. :( :)