1994 Ford Explorer engine swap

My 4.0 engine has finally given up the ghost after 200K+ miles. I obtained a replacement 4.0 from a local junkyard in very good shape. I took off the valve covers and intake manifold and it was very clean. The original engine had a CMP sensor on the back of the block on top of the oil pump drive. The engine that I bought is identical exept that that it just has a blank bolted down over that spot. There were two square

16 pin connectors that went off to the left side in front of the original engine and on the replacement engine, they were round and one of them only had 8 pins so we swapped wiring harnesses. My questions are: how can I tell what engine I bought,where could the CMP sensor be, is the oil pump drive in the same spot under that blank, and, can I transplant the CMP sensor?