Hello! 81 Dodge D150 with a 273 V8

It's a 318. That's OK cause they are easier to find parts for!!

PM = Plant - Mound road assembly plant
318 = CID
R = regular fuel

The 2267 should be the build date using the 10,000 day calendar, and 953 should be the 953rd engine built that day.

Someone more knowledgeable will confirm.