Chevelle upper rear control arm frame mount holes

[Mr. Anderson]

I've searched but haven't found my answer.

While cleaning my frame before painting ('66 El Camino), I noticed that the upper control arm mounts have two sets of holes. Mine appears to have used the lower pair originally.

What was the reason for the second set? Which set is better for handling purposes or does it make a difference?

Thanks in advance.

[killer69]

if there are 2 sets of holes the lower ones will be the better ones as far as the instant center goes. with GM who know why they are there.

[Mr. Anderson]

That's kinda what I thought, thanks for the reply.

The distance between the holes center to center using my eyeball measuring tape is about an inch. I'm wondering since the car will be lowered at least that much, if the upper holes would be in a better spot for the factory intended geometry. Then again, it might help like you say to keep them in the bottom.

[MrQuick]

Actually makes it better lowered....you should adjust the lower control arm hole at the axle to level the arm.