I have a T56 and 4.10 gears and the only problem i have is it whines ONLY in 6th. Is this because of the big overdrive and steep rear gears. Its only at a part throttle cruise, if i get into it or let out of it it mostly goes away. Any help is appreciated. The only thing ive seen in searching is people thinking its the rearend, and its DEFINATELY coming from the trans. P.S. The trans is a FRESH rebuild. Thanks Prorac1

 

Mine does the same thing. i think its because your exhaust is at a lower volume cruising in sixth. 4.10s are loud anyway. turn up the stereo and get over it. thats what i do anyway.