What do you think is the most difficult part of the 4l80e swap?
Sent from my SM-G935T using Tapatalk
Wiring. You can either replace the entire body harness with one intended for an A2-series HMMWV (expensive:$1000; and very labor-intensive: entire body should come off, or special tricks must be done) or build an add-on harness that runs the wires and connectors you need for the transmission.
As well, you'll need to purchase a transmission control module ($200-400), 12V relay, 12V circuit breaker, A2-series brake light switch, crankshaft rotation sensor, and fan cutoff switch (to replace kickdown switch). To mechanically use it, you'll need a new 4-speed shifter (has park and overdrive positions), trans to t-case adapter, a new crossmember, an NP242 transfer case, and you must replace the propeller shafts going to the front and rear differentials. Of course, you also need the 4L80E transmission with its appropriate sensors...either one pulled from a HMMWV or one that's built up to "RV-spec" with the shorter 4WD output shaft and housing, as I've seen passed around by several people.
Much of the wiring headache can be avoided by using some standalone, aftermarket controller, but I have to say that you're on your own with wiring and sensor requirements...they typically don't require as much, but aren't going to be sealed and reinforced like the military TCM and the only guarantee of its success is any claim by that manufacturer.