donor vehicle questions

[dieseltech619]

I have a line on an 04 2500 hd 6.0 auto 4x4 wrecked in the rear, trans has been sold and wouldn't be usefull for me being 4x4 any way.

i have done alot of reading on this forum and others and can't seem to find concrete answers to these questions

I plan on pulling the valve covers and making sure the top end looks clean, I also plan on using a custom harness. Besides inspecting the engine what other parts should i be looking for? ecm, throttle pedal, tac module?

what is the tac module and where is it located?

I was also considering taking the fuel lines and trans cooler lines as i might be able to reuse a portion of them

Will i run into any issues because this was originally a 4x4 setup? not sure if there are any special provisions in the ecm or of the engine that are 4x4 only?

thanks for your time and help