Questions: Fluids and Wiring

I would put Valvoline 75/140 Synthetic in diff with GM Friction Modifier if its a clutch diff. My trans has a Castrol Syntorq sticker on it which is now sold only through Mopar and is a 85W gear oil that is a very specific formula. Make sure what your trans came factory filled with. I have Redline MT-85 in my trans now and so far I like it.