I'm agreeing with Jeffy... The vibration does sound like the motor mounts... Especially if it goes away upon acceleration. But Jeffy was first on that one, so I'll give it up to him.
Although for a sure win of the $20.00, I'll give you a buck to see how big of a burn out you can do!! Even a tiny one on a gravel road. Then take my prediction for broken spider gears, or side gears in your D35 axle. :twisted:
What about your water pump? fixed that yet? If you haven't, much like the distributor cap & rotor, I highly recommend buying it from the dealer. Auto part water pumps, even though they're guaranteed for life, does you no good on the side of the freeway, or trail. Screw the guarantee and go for the dependability. The cap & rotor are usually good for 3-4 years from an auto part store, but they last an easy 4-5 even 6 years from the dealership.