I am hearing a squeaking noise from the tranny when accelerating, goes away at about 40mph, comes back when almost stopped, let off the gas it goes away altogether. Any ideas? It is a 6.0L with 4L80 tranny.

I am hearing a squeaking noise from the tranny when accelerating, goes away at about 40mph, comes back when almost stopped, let off the gas it goes away altogether. Any ideas?

have to be more specific.. is it the 4L80 or the allison. what engine? 6.0L 8.1L or 6.6 durmax diesel?

I am hearing a squeaking noise from the tranny when accelerating, goes away at about 40mph, comes back when almost stopped, let off the gas it goes away altogether. Any ideas?

this is usually the drive shaft CV joints...drive for a few miles and then see if these joints are hot...or leaking grease ...if so it won't be long the noise will become clunking, and vibration...

replace joints before this occurs or it may cause other damage..

replace joints before this occurs or it may cause other damage..

I agree, replace it better for Chevy 2500HD.