I have a heavy driveline vibration at 2,000 RPMs?

Hi,

Have you checked the universal joints on the driveshaft? It sounds like you have one that is worn.

Take a look at this link and let me know if it is helpful:

https://www.2carpros.com/articles/how-u-joints-work

If I recall, some of these had a three-piece rear drive shaft. If that is the case with your truck, there is a center bearing between the driveshafts. See pic below. With the vehicle blocked so it can't move, and the parking brake engaged, place the truck in neutral and see if there is play at any of the joints and the center bearing.

Let me know what you find.

Joe