irrational

Im in a situation where i can get either the earlier 4l80e or the later 99+ 4l80e. Its going to be behind a 4.8 and going to be turbo'd in the future. shooting for 5-600hp eventually. Currently tuned with hptuners so i can do whatever i need to do with tuning. Ive also found very little information about the electronic interchanges between 99+ and the earlier transmissions. Im assuming nothing has changed or been added that the 0411 pcm would not be able to handle but im unsure.

The person im buying the trans from has offered both early and late years to me so im looking for some input on what i should go with. Ive heard the 99+ had numerous updates, but ive also heard rear planet failures are more common. This is going to be a stock trans for now, but im seeing that valvebody and converter later on should take care of me when i do get the turbo on.

Thanks for the help.

SnIpEz

iTrader: (4)

GM re-designed the late models specifically to prevent rear planetary failure by switching to a revised lube circuit, though it was never much of an issue to begin with so it was a moot point. What you heard is largely unfounded. Are they both being offered at the same price? If so, may as well go with the late due to a few minor improvements such as the Hi Energy clutches. However, the early models also have a beefier OD roller clutch, which certainly doesn't hurt.

clinebarger

'94 & up use the same electronics (Compatible with your 0411 PCM)
The Lube circuit changes were made for the '97 year model.
I cant recall anything major in '99 besides the LS cases with the top bolt hole.
The later/Lower mileage unit is the one you want, 4L80E's are stout units but they do wear out pulling loaded trailers for 100,000+ miles.
As far as the OD roller clutch.....Don't drag race in D4, Put it in D3, The Overruns come on & will protect the OD roller clutch shock/failure.
Rear Planets failing isn't a concern on TH400/4L80E's.

irrational

Thanks for the insight guys, ill ask him about the newest unit he has thats rebuilt.