So I talked with circle D out of Texas earlier today and they advised against using the 6l90e that is in my truck for the power and weight I'm shooting for. Next logical call was to RPM Transmission to look at getting a 4L80E built for the truck.

Now that's all taken care of, what are you guys doing for driveshafts and transfer case options? My truck already has the manual shift case which I have been told is the strongest unit available factory. Also, currently the truck has steel driveshafts. Do I need to look at 1410 or bigger joints and aluminum or carbon shafts? Will they hold up to the weight of our trucks?

 

The trick with all of the transfer cases is don't shift in and out of 4wd under power or during a run. I have hit my 250k mile stock one with 1100ftlbs and 4 slicks and its just fine.

I used a 3.5" steel rear shaft and a 2.75" steel front shaft. 1350 joints on the rear and stock size (1310 maybe?) joints on the front.

 

How much power are we talking?

It seems the 6L80e are good for 500-600hp no problem with a good tune in a full size half ton. I would think the 6L90e is a tad stronger and can do that kind of power no problem even with some extra weight if this is a 3/4 ton truck and depending on cab config.

 

Power is north of 1000. Truck is regular cab long bed 4x4 3/4 ton. Circle D said at my weight(5k+) they could build one for the abuse but don't know how long it would handle it because of weight issues. Most of theirs are 600-800hp with a few at 1000.