Driveshaft hitting trailing arm crossmember

[68c10airstream]

Take a look at the crossmember opening to find a scratch mark where it made contact with the driveshaft. If it's on the side of the opening, take into consideration the positioning of the rear end. Is it shifted to one side because it needs an adjustable panhard rod?

When i did my ls swap in my 68 c10 i felt the old style motor mounts with slider positioned the engine too high. Still a good product but i took the approach of getting my ls as low and rearward as possible. Used f body pan. 2001 organ donor motor mounts and fabbed up my own frame brackets. This combo has the oil pan about 1/4" away from the steering center link in the straight ahead position.

This lowered the front of the engine and actually pitched up the rear of the trans a bit. Ujoint angles were close enough not to worry. I have lowered my truck 2 1/2" in front and 4" in back plus 1" blocks and nothing rubs anywhere. I did install a porterbuilt panhard rod and centered the rear end in the frame. the drive shaft did rub a muffler untill the panhard rod was installed and centered.