OP
Colonel Monk
Silver Member
Buy Acme threaded rod and nuts and make your own. That's what I did when I made some tall jack stands. The acme threaded rod was on sale at Enco, IRC, for $12 for 36", which I immediately cut in half to make two 18" pieces.
A one inch diameter 36" length of acme threaded rod would make several clamps like what you want.
Good luck.
That's a good idea too. Nowhere around here I'm going to find 5/8 bolts anyway.... Acme threads are just easier to turn under a load.