It might be different now, but years ago(20), only replacement gears were available for the pump.As there was no complete oil pump unit available to replace as a whole. Similar to a V8 Buick that has its oil pump built into the timing cover, and only gears to freshen the assembly. It was always my belief that the pump housing itself was permanently braded to the block, as was described earlier by the two round head attaching rivets or brads. Since I was familiar with other engines that had a non-serviceable pump, I never really questioned the removal of it. Other than having to drill the round head brads out, and replace them with bolts to reattach it to the block. Its been a while since I have really payed any attention to one. I've got a complete 216 to look at more closely.
