My '98 Z-28 only has 38k miles on it, and it has started giving this weird vibration in 3rd gear. If I'm maintaining low rpm it's fine, but soon as I start to accelerate, I feel this weird vibration, like the driveshaft is WAY outta balance. But, it only does it in 3rd gear under a load, and if you free rev the car it doesn't do it at all? Do me a favor and tell me that it's nothing to worry about

I've got a D&D T-56 to go in at Christmas time, but I have to make it til then, and still make a trip back to Texas at Christmas time. I noticed tonight that the vibration was significantly worse than before, also..I don't know if it makes any difference, it was also alot colder than it has been lately.

TIA,
Jason

 

It sounds driveshaft related to me. Could be a joint going out.