Ok so I've got a 98 ZJ with the 5.2, auto tranny, and quadratract. When I first start accelerating and the truck is still in 1st gear there is a whining sound. The best way to describe it is it almost sounds like the cars do on the Jetsons but more subtle. After the truck shifts into 2nd it goes away and drives just fine. The truck has 274,000 miles on it and I have no idea whether this is the original transmission or not. I do know the fluid level is good, its still red and doesnt smell burnt. Should I be concerned about this or just leave it be and if things get worse then worry about it?

 

It could be from a bad planetary gear set, drive it until it dies. Clean fluid, functions correctly, leave it be.