im building a strocker motor and taking out the T56 for a 4l80e. i know i want 99 or so and up tranny but is there a beter year that i want?

 

99-2000 would be optimal. In 99 they got wider planetary gear sets in the back. In 2001 they went to a different roller clutch design for the overdrive that was supposed to be improved. Unfortunately the smaller rollers do not hold as much torque. I've personally confirmed this by roasting one myself. A 1999 or 2000 will also have the center bolthole in the bell.

 

oh btw i have 2004 silverado with a 408

 

thanks for the advice

 

The 03+ transmissions have more updates. Any 99+ will work but the 03+ ideal.

 

I read starting in 97 they changed the low/reverse band servo piston to a weaker design. The pin can eventually punch through the piston and cause the not overly common but infamous 4L80E no reverse condition. I've seen this on a handful of 80Es that otherwise work perfect. Mine is a 96 so I hope I'm safe.


One thing to help you sleep better at night though. Doesn't matter what year of 80E you get, its still going to be leaps and bounds better then a 4L60E.

 

Not trying to hijack the tread but if I took out a 98 4L80E and installed a 06 4L8E would the programing and harness, lines be the same?

 

Yes.
Leave the PRND21 switch plugged into the harness on the truck and remove it from the shift linkage shaft before removing the original transmission.

 

GM changes the calibration a LOT for all transmissions (even if the transmission internals are exactly the same). I wouldn't sweat the programming much. Biggest exception is the very early 80Es (91-93) as the wiring harness/PCS is different. Both will get replaced on a rebuild anyway.