62 V8 crawl box?

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Jan 18, 2006
Reno, Nevada
Hey all,
For you 62 guyz that have done the V8 swap AAAAAND run a reduction box behind it, what did you use to do it?
It seems that most of the crawl boxes are not compatable with the 19 spline t cases.
Did you swap in 60 series t case?
How does this work?
Planning on using a 4L60E tranny for the set up behind a 5.3 Vortec.

Im so challenged on this topic its embarrasing.:eek:

Thanks in advance!

The 60 case is 19 spline just like the 62 t-case.

Add this to the list of things to buy...

P/N 50-9305 Advanced adapters

Advance Adapter

Advance Adapters is proud to offer our shorty 4L60E to Atlas 4 speed transfer case adapter assembly. The adapter is only 1.625” in length and includes a GM VSS kit incorporated within’. This adapter assembly is for exclusive use with the late model 4L60E with removable bell housing and includes a new 300M billet output shaft. We also include a heavy duty transmission mount that bolts to our adapter housing. :D Why did n't I think of that! :bang:

Off course there are many bolt on's for the 4l60E...But you need to look for Chevy full size parts Think that it is an Orion box.
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The Atlas is without a doubt the way to go as long as you change rear axles to a center diff location. I ran a Klune which will bolt to the 4L60E then there is an adapter to run the split case after the Klune. It is about 8" long total and works really well. Gives similar ratios as an Atlas.
4L60E/NP203/Split tcase.

4L60E/NP203/Split tcase.


I needed a new tailshaft from AA for my 700r4 (4L60E the same?) to mate up w/ the old 203. Grab a OEM TH350/203 cast adapter mount while you are sourcing the 203. Mudrak sells the 203 to Splitcase adapter. New crossmembers and d-shafts are in your future...But so are triple shifters;)

Search for Calfj60's rig. He had the set up just about done...

From Mudrak's site (just picture the 4L60E w/GM adapter instead of the 4-speed)
Thanks guyz...
Ive been reading the AA literature, and the way I was reading it, it sounded like I needed to find a 16 spline t case for any of the stuff they offer.
So, get an NP203, couple that to the stock split case and that will work? Mace, would wouldnt happen to know off the top of your head the ratio for that would you?
Anyone know anything about the marlin boxes running with a V8?
Ive heard that they wont hold up behind a V8, but Id like clarification on that...
Ill be keeping the stock rear axel. Am I really gonna be running into issues with that?

Thanks all,

I know they can hold up to a small block chevy. The problems I've seen with them is in the output on the second mini case. In your case, I would think you'd be alright and you would have more gearing than a 203 weather you run a stock mini (2.28) or a 4.7 set in it.
203 is 2:1

Bob is running a C6/203/splittcase

Marlins boxes are pretty strong. I am running dual cases in my 40 and beat the tar out of it with 40's and almost 200:1

If you start shattering axles, go from there. There is a good chance you won't. If you do, there are poly performance options or just pony up for a 35/40 spline 9".
Don't forget that the later (97 up?) 4l60e's have the round 6-bolt pattern that is not compatable with the earlier adapters. You might be able to use stock GM parts to bolt it together but without a t-case adapter in front of me I couldn't tell you.

you do not need the advanced shaft to mount an early 4l60e to a 203, oyu can use a 241 adapter & redrill the face of the 203. This will add about 2" over the AA shaft w/ th350 adapter.
Hey sixty, can you delete the tranny out of the computer to run a TH350 behind one of these pretty easy? I'd assume you would need a different flexplate too? Anything needed to run a th350? tv cable?

Hi-jack over. :)
I would imagine it would be pretty simple to remove the transmission from the ECM (depending on model and year). I think EFI live has that capability or there are companies out there that can do it.

I think a 4l60e is a much better transmission than a th350.
I would imagine it would be pretty simple to remove the transmission from the ECM (depending on model and year). I think EFI live has that capability or there are companies out there that can do it.

I think a 4l60e is a much better transmission than a th350.

I agree that the 4l60e is probably better but I already have the th350 and it is freshly rebuilt as welll. Are the 4l60e 27 spline? Any idea on the VSS?
Im an idiot I know, but how does the gearing numbers break down?
Like Mace said he's getting 200.1....Im assuming there is a formula that can get you those numbers.

Im looking for the least expensive route, and also the most bullet proof.
200. 1 sound fantastic to me...
Having never run deep gears before, Im wondering what I will need vs. what would be overkill.
The costs im looking at are phenominal for this whole deal.
The terrain im looking at is Rubicon, fordice, dusey...
Can anyone lend some assistance on what would be OPTIMAL vs. a pipe dream?

Im seriously learning this as Im going along!

Thanks guyz, this is great info!

Unless I was really on a budget I would use the 4l60e, since it has a low first, a lockup, robbs less power & is compatable with the 5.3 ecm.

As far as I know they are all 27spline.

Are you sure you want to go with a 5.3? I just got my exahust done and modified my TBI ecm with the EBL from dynamicefi.com. So far it is pretty sweet and the EBL with TBI should support well above 500hp. As a plus, my stroker is compatable with off the shelf SBC speed shop parts so its no problem getting any needed parts locally.

I should be updating my thread soon with info and pics. keep myour eye's on craigslist and you could find a build SBC/BBC that you could swap most of your TBI parts into. Just a though :)

Feel free to post any questions in my Hardcore forum thread.

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