The short bolts measure 1 5/16 as measured from under the head of the bolt, so 1 1/4 length under the head may work if you can’t find the 1 5/16. The long bolts measure 2 13/16 under the head so 2 3/4 should work. Remember the head has a dowel on each end to locate the assembly.
The two long bolts get the two short clamps, the shorter bolts get the longer clamps.
