4L80's and 4L80E's have a GVW rating of 15,000 lbs or more depending on clutch packs used - 3/4ton and 1ton trucks have these trannys and they will also go behind Duramaxes in 2002 burbs. Much stouter than the 700R4's which are considered light duty trannys. I have had several people tell me that the computer interface for the 4L80"E" is not that tough to figure out. You can buy a programmable "smart" relay with 16 digital I/O and 2 analog inputs that could manage the function for under $100. Here is a decent link someone else posted a few months ago that clear up some of the questions about GM trannys, ratings, etc.
tranny link
