ok heres the deal sparky. I bought a 99 silverado short bed standard cab 2wd pickup from a buddy real cheap, it was wrecked but everything was fixed. The truck had a 4.3L with a 4l60. I have a 99 ls1 from a previous project, i now have the v8 harness and 4l60 from a other truck because the truck came with no motor or trans. i have everything plus the v6 mounts and a set of v8 mounts. the problem is i have the tailshaft bolted to the crossmember but loose enough to move the engine back and forth. i have long tube headers when i lift the front of the motor at a slight elevation just above the mounts the engine and mounts dont match up.
if i put the motor mounts on first then its all a mess. some one please help give me some ideas, i was considering cutting a plate out to go inbetween the mounts and the engine but im just not sure

 

Which motor mount bolts you talking about? I unbolt the 6 from the topside & leave the mount bracket bolted to the frame. Taking the headers off will be ur best bet!

 

I think I remember something about there being different motor mount sets...might be something to look into.