Totally just stumped have a 84 stepside f-150 4x4 c-6 302. I'm hearing ALOT of noise coming from the drivetrain when running about 35 and 55 mph also when under acceleration when you let out about 3/4 of the way it's a loud rattling almost wrapping noise coming from the tranny could this be bands?
I also recently replaced the t-case but it was making this noise before that

 

It's a 30 year old truck.I would start with the universal joints. Have you changed the differentials oil yet?.You should be able to tell unserneith if you have slop in your universals.