Looking for a trans/transfer case combo...

[tjrugg03]

I've got a shortbed, 4wd, 68 GMC K15 that I'm in the process of bringing back from mothballs. It's got a remanufactured (later style block) 350SBC. HEI, and a painless performance chassis wiring harness. Finally got the thing running a couple days ago and I've got a pretty good hunch that the transfer case linkage is wonky. It won't come out of 4wd. Front hubs are free and it still tries to spin the front drive-shaft. Unfortunately, the 4" skyjacker lift is causing some binding in the front drivetrain. To temporarily remedy the situation, I removed said driveshaft. No big deal right now, because it's spring and it's gonna be a weekend runner for the summer. My ultimate goal is to run a 6.7 Cummins with Dana 60s front and rear. Problem is, I want to do this over time. Piece by piece while, for the most part, keeping it running.
My main question is this; Is there a transmission/transfer case combo that I can run behind the 350 for now, and eventually run behind the Cummins?
I understand I will need to change parts like the input shafts and bell housings, but is there something that I can use behind both engines? I enjoy driving a manual, but I like the convenience of an automatic, so I'm impartial either way.

This is my first attempt at a restoration so I am still learning a LOT!
Please help. Thanks!

[DieselSJ]

Some might say to run the 4L80E, but unless you spend some serious $$ on upgrading the internals a 6.7 is just going to tear it apart. Look at an Allison. So you are either going to spend a bunch of bucks on upgrading the 4L80E or you are going to spend a bunch of bucks on a controller for the Allison.

IMHO, get the 6.7 with trans and transfer case and all the wiring and electronics and do it all at once.

[dennislbrooks]

Take a nv4500 and the 241c . Then get a dodge bellhousing with the cummins. The nv4500 should/may be same pattern as a dodge/chevy truck bellhousing. Then use dodge bellhousing when cummins goes in. Linkages may be an adventure. dunno

[clinebarger]

Originally Posted by DieselSJ

Some might say to run the 4L80E, but unless you spend some serious $$ on upgrading the internals a 6.7 is just going to tear it apart. Look at an Allison. So you are either going to spend a bunch of bucks on upgrading the 4L80E or you are going to spend a bunch of bucks on a controller for the Allison.

IMHO, get the 6.7 with trans and transfer case and all the wiring and electronics and do it all at once.

The only upgraded hard parts a 4l80E NEEDS to hold 1000 ft lbs is.....
E4340 billet Input Shaft.
Forged steel Forward Hub.

I have a customer in the 9's with a Duramax/4L80E combination with the 2 above parts running 200 PSI of line pressure leaving on a Trans Brake.

Allison 1000's have VERY strong hard parts, I am not questioning the strength of unit, But.......As you stated.....Controllers are expensive, They also have a odd-ball 29 spline output shaft that no passenger side drop T-case will fit.

I am not the biggest fan of the 68RFE that comes behind the Cummins 6.7L, Also the T-case is driver side drop.

To the OP.....Why not a '06-'10 Duramax out of a Express/Savana Van, You can do a 4L80E with a NP208/NP241/NP205 now, Then buy a Duramax out a van with the wiring, ECM, & TCM.....It will control the existing 4L80E WITHOUT a aftermarket controller.

[tjrugg03]

As much as I like the Duramax, I'm a bigger fan of the Cummins. If I could find an early '90s dodge with the body all torn up, I'd just do a body swap, but in my area, the likely hood of that happening are slim to none. I'm open to all suggestions and I hope to come up with a good combo soon.
To those who know t-cases fairly well, I ask whether or not I'd have to spend an arm and a leg on new internals or if they can usually handle the torque from a 6.7?

[DieselSJ]

Originally Posted by clinebarger

The only upgraded hard parts a 4l80E NEEDS to hold 1000 ft lbs is.....
E4340 billet Input Shaft.
Forged steel Forward Hub.

I have a customer in the 9's with a Duramax/4L80E combination with the 2 above parts running 200 PSI of line pressure leaving on a Trans Brake.

Allison 1000's have VERY strong hard parts, I am not questioning the strength of unit, But.......As you stated.....Controllers are expensive, They also have a odd-ball 29 spline output shaft that no passenger side drop T-case will fit.

I am not the biggest fan of the 68RFE that comes behind the Cummins 6.7L, Also the T-case is driver side drop.

To the OP.....Why not a '06-'10 Duramax out of a Express/Savana Van, You can do a 4L80E with a NP208/NP241/NP205 now, Then buy a Duramax out a van with the wiring, ECM, & TCM.....It will control the existing 4L80E WITHOUT a aftermarket controller.

Also a billet 6 pinion rear and a 5 pinion front planetary. He ain't runnin no 9 second truck with a 4L80E with just an input shaft and steel hub and stock planetaries...lol. And don't forget the torque converter.

I've been looking at this exact same thing for my R30. A 4L80E built for that much power with a controller isn't much different in price than the Allison setup with a controller. The Ally also gives either 5 or 6 speeds depending on year.

All that being said, I'm personally leaning towards the 4L80E because it fits the chassis without needing any clearance on the firewall or trans tunnel.

[clinebarger]

Originally Posted by DieselSJ

Also a billet 6 pinion rear and a 5 pinion front planetary. He ain't runnin no 9 second truck with a 4L80E with just an input shaft and steel hub and stock planetaries...lol. And don't forget the torque converter.

With STOCK 4 pinion front & rear Carriers! I built it myself. It's in a fairly light backhalved '85 C-10, I'm far more concerned about the O/D Carrier & O/D Roller Clutch, IF something happens to the O/D Carrier.....It will get a billet piece! Yes it has a Billet front cover triple disc converter.

This is an interesting subject to debate, How many 4L80E /TH400 planetary failures have you seen that were not from lubrication issues? If your changing ratios.....That is a whole different story, They NEED more pinions because the reduction in size of the Sun Gear.
To many "Billet" parts only make your wallet lighter with no PROVEN reliability over stock pieces.

I guess it would blow your mind if I told you it has stock replacement Borg Warner frictions?