Did a search for "what does this fit" etc, and found nothing, so here is my question. I did a swap deal with a friend, who had these cylinders, and I am not sure if they are just altered, or is they fit something that I have never ran into. there is no fire ring, and the only castings are a R and a shield looking logo. they came with fresh bore and good pistons and rings/wrist pins and keepers. I measured them and they seem to be stock 74 inch. The headbolt pattern does not match shovel heads or pan heads.