ok here's sitch, I have a 05 2500 , witha 48re, I want to swap to a 6speed I found a doner truck with everything even steering column and Engine ecm!, thing is,is its a 2/of 04 year truck, I am wondering what electronics I need I can have the whole wiring harness both under dash and under hood, Only thing is, Is they sold the engine but kept the ecm, so there is no engine harness, it went with the engine, and this truck has the dreded gray key, and the electronic transfercase, mines the manley lever,and NO GRAY KEY, here I am wondering, I read somewhere on here that might just need the engine harness?. the transmission has the harness that goes to it and the transf,. I can basically have everything I need from this truck but I only want to use what I need to do it right nothing extra. without the sentry key stuff.

any ideas... you guys wont belive the price, only 60000 miles on truck Never towed anything.$2500 for everything.

 

When I installed the replacement engine into my truck it came from an auto and I swapped in the ECM that came with the engine. The harness bolted right up. But the truck wouldn't run.

I have the gray key on my truck and it didn't like the new engine ECM. Apparently the engine ECM's serial number has to be coded to the truck's body ECM otherwise the sentry system won't let it start. I swapped back in my original ECM and it fired right up and ran fine.

If you don't have the sentry system and swap in a different ECM it might not care.

 

good point I dont want to swap my ECM as my truck runs Real strong dunno about the other,also the 04 has the cable throttle mine is fly by wire,I know I could prolly have the local dealer flash my ecm if needed to a Manual? instead of auto isnt that correct?. No I dont have the sentry system, and dont want it, I also dont want the electric transfercase, the one that came from the 04 truck is a 29 spline count, isnt the auto from these newer trucks the same now.?