4L80E to transfer case.
The CUCV trucks all had TH400 transmissions with a 32 spline output shaft. All of the trucks had either a NP208 or NP205 married transfer case. If you find a 4 wheel drive 4L80E with the pedestal/transmission mount bolted to the back of it. Then any CUCV 208 or 205 will bolt right up to the transmission. The 4L80E will bolt to any GM 6.2 or 6.5 that had a TH400 behind it without changing anything at the engine or flex plate.
However, the 4L80E is about 1.5 inches longer than the TH400. The stock CUCV cross member will have to be moved toward the rear axle 1.5 inches. By happenstance, that is exactly the bolt spacing on the frame rail of the CUCV trucks where the cross member bolts in. What was the rear cross member bolt hole in the frame now becomes the front cross member bolt hole. Bolt the cross member up with the front bolts and drill new rear holes with the cross member as the template.
Of course, the transmission shift linkage will have to be lengthened a few inches. So will the transfer case shift linkage. If you are not doing a lift at the same time. The rear drive shaft will need to be shortened and the front drive shaft might need to be redone longer.
The CUCV TH400 pedestal mount is cast iron. It will not bolt directly to a 4L80E. It is just a hair too big. Think SAE standard on the mount and metric on the 4L80E. The aluminum 4L80 mount fits the transmission and the transfer case. I did, just for fun turn a cast iron mount down with a hand file in a short amount of time to fit a 4L80E. I used the aluminum one because it was right and I had it.
Back to the 6.5, 4Bt, 6BT debate. The Cummins engines make more torque at a lower rpm than the GM engines. Dodge had a lot of trouble the first years of the 6BT keeping torque converters alive in their automatic transmissions. Same with clutches and transmission input shafts on the manual transmissions. That is why there is a diesel version of the NV4500 used by Dodge. The original version would break too easy.
I don't know who manufactured the Frito-Lay delivery trucks with a 4BT and TH400 in them. Just that when they were sold off at super low prices they became very popular. I would imagine they are where most of the available 4BT engines people can find at a good price today came from. Frito-Lay apparently had a massive TH400 failure rate in those vehicles. They went to the NV4500 I think because of it in the later ones.
So, yes a TH400 or its overdrive half brother the 4L80E can be bolted to a 4Bt or 6BT if you have the GM Cummins rear engine plate which is very expensive all by itself. Go over to 4BT.com and there are dozens of threads by people who have tried it. Most end badly for the transmission and the owners wallet.
Then there is the Charge Air Cooler needed to make the big power out of a 4BT or bigger power out of a 6BT. I wrote charge air cooler because intercooler isn't exactly correct or applicable to the three main ways of cooling the turbo charged air entering the engine.
The 1992 6BT Dodge trucks without a CAC and without a waste gate had almost the exact same hp and torque numbers as a Banks dealer option equipped 6.2 truck. The 1993 6BT got an air to air CAC along with another ring on the piston to handle the higher pressure. They had higher numbers than a Banks 6.2 which didn't have a CAC. Then Cummins went to the P7100 inline IP that could be turned up to make huge power. With the increase in power, the CAC kept getting bigger too.
There is not much room on a square body Chevy truck for an air to air CAC. Especially, with the engine oil cooler, power steering cooler, transmission cooler and condenser between the grill and radiator. People have done it though. Mostly with a 2003 Duramax air to air CAC modified along with some radiator modifications.
An air to water CAC can be made to fit under the hood without a bunch of large tubing under the hood. It does need a water tank, water radiator, a pump and the plumbing for it though. Most people that have used it say they are great for drag racing length runs but useless on a long up hill climb in 100° outside temps. Especially if you have 3 or 4 long climbs in a short amount of time. The water gets so heated it doesn't cool the air any.
Mist injection is another way of CAC with mist water or alcohol injection. There are some true believers on the internet out there. They use gallons and gallons of liquid getting squirted in above a certain boost or EGT. It works great, but a 50 gallon water tank in the back just isn't my thing.
The CAC discussion is there because without one, sustained power just isn't possible. No matter what super engine is under the hood. So, look at the numbers of a 1992 Cummins in a Dodge D30. That is probably the power level a 6BT in a square body truck will be at unless a CAC is added. With that in mind, is the extra expense, weight and labor of putting a 6BT in the truck compared to adding a turbo to the already in the truck 6.2 worth it?
4BT engines are priced so high with power numbers the same or below the 6.5 turbo with a 2,600 rpm redline that again. Is it really worth the effort?
