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Discussion Starter · #1 ·
I have a '56 CJ5 with a 283 SBC mated to the original T-90 3spd and Dana18 transfer case. The question I have is what adapter(s) is(are) needed to install the GM SM420 granny 4spd out of a mid '60's GM pickup? It should just bolt up to the engine, but I'm not sure what will need to be done to mate it to the transfer. Also, I haven't purchased the tranny yet as I'm not sure if I should find one out of a 4x4 or if a 4x2's transmission will work. Any ideas? Thanks in advance for any inputs...

 
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Discussion Starter · #2 ·
I used this tranny on my jeep and got the adaptor from Advanced Adaptors.
http://www.AdvanceAdapters.com/ It worked great.
You might want to check out Rube for an adaptor as well. Phone # 559-299-5736.
I don't believe it matters if it's a 2wheel or 4wheel tranny.
 
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Discussion Starter · #3 ·
if you can i would go with a sm465. better tranny, easier to find parts for. the 420 is notorious for losing second gear syncros which are part of the gear. getting very hard to find. but the 7.00 1st gear is nice.

dan

I do not intend to offend,I offend with my intent
 
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Discussion Starter · #4 ·
SM 420's are 10.430" in length and SM465's are 12.000" so if you are maxed on driveline angle already you might want to think about the 420. also the 420 has a lower first gear (7.04 to 1) versus the 465 (6.54 to 1).The 465 is stronger and has a reverse light switch that is a plus, but I think you will have to have your bellhousing bored out to accept the 465 because the 420 uses the smaller 4.686" belhousing hole and the 465 uses a 5.125" hole.aside from that you only need one adapter between the tranny and transfer for either of the trannies. I believe both 2x4 and 4x4 420s will work since all 4x4 420s were divorce mounted. Good luck!

JesseJ

 
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Discussion Starter · #5 ·
How long is the T-90? I'm going to have my stock springs re-arched to a 4" lift which should end up at 2.5" when installed and then I'm going to add in the Revolver shackles for an additional 1". My drive line angles shouldn't be effected much by this mild of a lift, however I'm not sure how much my stock drive shafts are going to need to be modified. I haven't pulled the T-90 out yet, and I haven't measured the length. This is a weekend project rig since my @#$! job keeps me during the daylight hours. Thanks for the reply and the info... d8^)

 
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Discussion Starter · #6 ·
I shot Advance Adapters an e-mail to get a price on the adapter. No response yet, but hey it's the holidays! Thanks for the info and have a good Turkey day!

 

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According to the Advance Adapters book the T90 is 8" long and the sm420 is
10" long. The adapter you will need is either the 50-2400 (4.5") or the
50-2401 (4"). The difference is that the first one uses a new full main
shaft and the second one uses a spud shaft.

C-Ya.....................kh
 
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