PROBLEM SOLVED:

It was the drive shaft.

When I went and rebuilt my truck I ended up taking the solid axle out and replacing it with a 1969 rearend. So I had to replace the driveshaft with a custom one.

Well I went to Inland Truck Parts in Kansas City, and had them make me a new one specifically for my truck. It works great! Wow, now I can go fast!

Thanks for all the posts.

And sorry, but I think I did not mention the driveshaft, rearend swich.

CHEVY
1950 3100,
1958 Fleetside,
1961 Fleetside,
1966 Suburban