Apparently if you are going to use a 99 4l80e, you have to use rear cooler line fitting which has a longer snout. If you don't the trans is said to fail. I think this is what the problem was with my trans that only lasted about 500ish miles, half of which performance seriously decreased. I am going to install the 80e rear fitting and see if that remedies the problem. If not, I will obviously have to replace/rebuild the trans. I'm not sure if 99 and newer units are correct as i heard of someone with a 98 who had a longer snout in the rear. Here is a link to a thread where this issue is discussed. Vince, seemed to stress the importance on this fitting to.
http://www.performancetrucks.net/for...s-help-485402/
2007 GMT900 CCSB 5.3 VTS2300 Twin Screw Supercharger, Doug Thorley LT's, True 3" Duals into Dynomax Race Bullets, Nelson Tune, 4L80e w/transgo HD2-D, Truetrac, 4.10 r&p
Need list: Stall, PLX 200 for my crappy AFR, X-pipe, GM 20's.