Here we have the set of two huge orange o-rings. You only need one afaik between the oil cooler and the block. The two little ones somehow keep the dipstick tube from leaking where it hits the oil pan (that's magic to me 'cuz they are wiggly... but they don't leak) They threw in a crush ring. Preesh. And the odd, pointed on one side, flat on the other, thick black o-ring is for the yellow oil fill cap.
These are the 3 (of 4) black, shaped o-rings and the larger orange o-ring that go between the two block halves. When these are missing from a set, it can really hamper your day. The 4th black shaped o-ring of the same size goes behind the oil pump. There is a very similarly shaped black o-ring ( the different one in the middle here) that goes between the block and the oil pickup tube so squint a bit when you decide what is what:
Rear main seals. They give us 3. I think because they have no idea how to write instructions. The rear main seal DOES NOT GET DRIVEN ALL THE WAY IN. I got even better at pulling my motor because I did not know that the first time. Fortunately my DP was kind enough to send a smoke signal. "...you.... are... a... retard..." it seemed to say. The rear main should sit basicly flush with the block. Subaru "mechanics" use a tool. ( <--- that should be a t-shirt)