Are you sure they are not numbered? Best choice now, is to see if there are any marks or features that would tie one to another. The real test is to measure them, torqued, with a dial bore gage. Also I would never return to that machine shop.
If you can't figure out which rods and caps go together. maybe ask the machine shop to figure it out or recondition the rods (with new bolts) at their expense for mixing them up on you. They need to learn from their mistakes.
