Rear seal question......Help

With the 360 engine they don't use the extra bits, you only get the 2 half circle seals. Another thing you can do is when fitting the 2 seal halves, don't have the parting line level with the block, push the seal in the block down on one side about 3/8" and the other side will sit up the same amount, and do the same with the other half seal in the cap. It is a bit of extra playing around but it will ensure there are no leaks, and use some RTV .