[sleepertoy]

So I got this t-case today. I realized too late it is a 21 spline. I was after a 23 I suppose but answer me this:

is it gonna kill me to use a 21?

My toy has the stock 3vze and I plan to run 2.8s in the front case and 4.7s in the rear.

Will i break this on moderate to serious trail running? Not really rock crawling...

I searched around and know I can get an adapter for either (right?) but didn't seem like anyone had any real strong feelings about the differance...

 

[sleepertoy]

dual 4.7s ARE YOU MAD MAN??!

heh heh well I was thinking strongly about dual 4.7s but up here in oregon I may want more wheel speed sometimes and that would be crazy gear reduction, much more than I think I could use. Not like I'm in Moab or somethin!

Anyhow, I figured just leave 2.8s in the front case and go with 4.7s in the back. With my 5.29s in the dif that'll give me like 333:1 or some such.

I'm going to see if the guy I got the 21 spline from will let me swap for a 23. That was model year 87 to 89 right?

 

[sleepertoy]

may as well be 23

Okay, after more research this is what I've figured out. After searching here I didn't find the answer to my question (information there but too spread out for me to piece together) so I'll post the following for posterity.

For my application (91 V6 SAS) to get 23 splines you need two 21 spline 4cyl transfer cases (non turbo). They need to be the top shifting kind.

Then you buy the kit (I think Marlin is the only who has it) which contains a 23 spline input (as stated by TR above)
shaft to replace the 21 that is in the OEM case.

So, basically you supply two cases, whatever gears you are going to use and I guess a gear shift if you don't buy Marlin's short throw setup.

I'm sure this is obvious to Camo and other folks but since I was confused I figured others might be too.

Interesting side note for V6 guys:

If you do a 4cyl case on it's own you will actually lose some gear reduction over the origianl chain driven case that your truck came with. The V6 case is 2.56:1 I think while the 4cyl is only 2.28:1. I don't know why you would do this unless you were just working your way up to better gears a few $$ at a time but is useful info noneethless.

 

[sleepertoy]

23

I'm gonna go ahead and use the 23 spline input shaft. I figure I haven't "cut corners" anywhere else on my rig so why start now.

but hey, I've got a rep for tossing money away, that's why I have a MSD igition, coil etc. We all make mistakes. heh heh

 

[sleepertoy]

Re: Re: may as well be 23

Actually, 3.83 is the 1st gear tranny ratio. Low range is lower than the 4cyl cases, but it's something like 2.56:1, not that much of a difference.

Ah, indeed.