SM420 vs 465 ??
 

Whats the difference?

the 420 has a bit lower of a first gear, and the reverse is on the driver side of the "H"...it might be a little smaller than the 465, too

I have been told the 465 is stronger than the 420. The 420 is supposedly shorter . Jeep guys love the 420 for the gearing and length.

yep, the 420 is about 1 1/2" shorter than the 465. It is also lower geared in first. I don't know about the strength difference, they both seem very stout to me. The 465 is easier to get replacement parts as they quit making the 420 in 67 or early 68.

Pont when you say shorter does that mean in length or height ? Will the 465 interchange i mean will it bolt up to the rockwell without any modifications ?

To bolt a Rockwell that was behind a 420 onto a 465, you would need the Rockwell adapter that goes with the 465. This is a rare unit, since it was 1969 only, IIRC.

The 420 was never married. (Actually, they MIGHT have been married 1 year, 67.)They used divorced t-case in 4x4 applications. The 465 is very strong and very common until the early 90's. www.advanceadapters has transmission dimensions in an installation guide. I believe it is free but their swap books are not. I have a couple of them and they are well worth the nominal fee of $8 or so.

Jose, the 420 is shorter in length and as Blazer1970 said, you would need to get the correct adapter to mount a 465 to the Rockwell. When I pulled the 420/Rockwell out of mine and installed the 465/NP205 combo, it moved my crossmember back almost 2 inches.

Mike C, my 67 had the 420 and Rockwell married so we know they at least did it in 67. I'll ask Breeh if his 68 was married or divorced.

My 69 GMC had a rockwell and 420, TC had 1967 stamped tag though.. I think Canada ended up with more of this combo in 69 in the GMC line. Brother has a 69 GMC with rockwell and 465. Both married tranny to transfer case in our cases.

Guess I was confused on what year the 465 showed up. Anyhow, NO trucks BEFORE 67 had married t-case and sm420. (Until proven otherwise, I'll stick with it!) :D In the US wasn't the 465 used in 68 and up?

I'm not much for crunching numbers but I think you are absolutely right, 68 up was the standard for the 465. I have heard of some 420's carried over to 68 but I don't think it's that common.