That's interesting but confusing at the same time. The oil pump mount is the only thing down there but the hole the oil pump shaft mounts into is the same diameter as the distributor shaft, so it would not have kept the distributor from sliding down in any case. (the oil pump is held in place with a screw and a lock nut) So, the only thing that would keep the distributor from going in would be the oil pump shaft (where the distributor tab slides in). Curious, but glad it is solved.
