Hello, I just purchased a 1970 K5 and need information on Bolt type and size to attach hard top to the side rails(double sided rails).

:crazy:

Welcome to the board from South Mississippi! I've moved this to where the experts are.:D

1st :welcome2: From West TN :hi2:

2nd Double sided rails? do you mean it has 2 different sets of holes?
or do you mean it's a double wall top? trying to be sure about needs

From what i have been reading, when people were talking about bolting the top from up under the rails, they referred to them as double sided.

My top bolts from under the rails and the top has threaded holes that match the holes in the side rails of the truck bed.

As you can tell, i don't have much experience at this, but i will....

You have a Double ;)