Need info on loose 74 caliper

You are correct about the "o" rings (really rubberbands - got mine in an anti rattle clip and mounting hardware pack!!!) they do fit on the caliper monting bracket in the groove that the pad fits in and they need to be coated all the way around outside with silicon lube (comes in the pack) to prevent oxidation, but I can tell you now from experience that they are junk. One of them that I installed in Feb. while temp was 60 shredded 1-2 weeks after it was installed and I haven't checked the other one for some time it may be toast as well. They both were coated with high temp brake grease in the mounting grove. I live in Pheonix, AZ and the temp hits 115 most of summer and dry as hell all year. The problem is that the caliper and/or mounting brackets wear beyond specs and then don't fit. But the companies that rebuild the calipers just send a rubberband with the ones they sell. In my case the caliper on the car when I got it was worn out dimensionally, but getting a rebuilt caliper is a gamble. And then of course what to do if it's the mounting bracket (there are no rebuilds that I know of). So your left either Mickey mousing around or getting new brakes. I haven't decided what I'm doing yet. Do some research and good luck.