06pcklm7

iTrader: (8)

Ok just got a 99 rcsb with 4.8 5 speed, Tranny gets warm doesn't want to do nothing at all... So I wondering I have herd of some guys doing a t 56 swap because the nv3500 isnt that great of a tranny for 400+ hp street truck. plus I have a 2001 ss love the 6 speed. Just wondering if any of u guys have done it and what to look for and all stuff ext... Thanks

gatorhead

iTrader: (4)

I have been looking for this kind of info for weeks now. I have scoured the net and read everything I could find. The stuff I did find was old, and incomplete information. I was hoping someone would step in here and chime in, but I haven't gotten much help from this forum at all concerning this.

I will share what I did find with you tho.....take it at will as it is stuff I read on the net and haven't really thoroughly checked it out. Also if you get any info that I ont post please share the same.

The NV 3500 is a medium duty truck transmission, more towards the light duty side. The heavier duty version is the NV 4500, but the sacrafice is the long gates and an unuseable first gear, granny low kind of gear, and there are alot of problems with 5th gear, although there is a fix out there for that. From all that I have gathered the aftermarket never really stepped up for the NV 3500.

So from what I have found the alternatives are the T56, The TKO 500/600/6060. The problem is that they are all very expensive. I have read that the T56 requires a tunnel modification and something about the center seat needs to be modded as well. The cross members dont line up and the driveshaft has to be shortened/rebalanced. There is opinion out and about that the gearing isn't right for towing or the weight of the truck and the tranny is too light for a truck. I would venture (no pun intended) to say that the T56 is a whole category stronger than the NV 3500. It also can be built to withstand whatever, and regeared for that optimal "truck" gearing. The GTO T56 has the best out of the box gearing for a truck. There could also be problems with the crank depending on years. I read in ine place that there is also a shifter that moves the T56 shifter forward and that can be used so there doesnt have to be a seat mod.

Everything I have read points me to an automatic. That being said I can't find a whole lot of info on that swap either. Again what I do find is old or incomplete.

Thats about all I can remember for now.......Iknow it isnt what you were looking or,and maybe someone can point us in the right direction. There was a member here that did the swap and did a great writeup, but the page is no longer valid.

vanillagorilla

iTrader: (1)

You're going to have to do some things to put a T56 behind a 99 4.8. There was a guy on here that did it a LONG time ago, and he had to make a plate that went betwixt the tranny and bell housing. Reason being is that, much like the 99 6.0s, the crank flange on a 99/5spd 4.8, sticks out more than on LS1's where the flywheel bolts on. This guy made up the difference via a plate so the slave and pressure plate all lined up. This caused issues with everything else. Driveshaft, cross member and everything else needed to more accordingly.

kren7604

I just did a t-56 swap into my 04 silverado RST rcsb, 4.8 5spd, I started out with just the t-56 swap. then also swapped a 02 Ls6 in... But my tranny is from 02 ws6. 98-02 will bolt righ up bolt for bolt, flywheel clutch ect. tranny x-member fits just fine!!! I have a KEISLER front shift conversion, which moives the shift linkage up to that secondary port plate on the t-56. With the front shift conversion it sits about 3" back from the stock NV3500. on the driveshaft the yolks will have to be swapped to accomodate with the t-56, not 100 % on if the driveshaft needs to be lenghtened or shortened, will know in about a week when i get back home workin on it again.. Heres my link with a couple pics of what the t-56 looks like installed, with a custom shifter..

https://www.performancetrucks.net/fo...do-rst-499325/

http://i1107.photobucket.com/albums/...6/IMAG0119.jpg