Here is the information you need on the peugeot engine type. Not sure about the car engine ID, but if you find it please let me know as mine is slowly falling to bits.

The MD21B was produced between 1979 and 1981. The engine is indeed
produced by Indenor (Industrie du Nord Est) AKA Peugeot XDP4/90. This was given to me by Volvo the other day, hope it helps.

Best of luck, you haven't got a spare water pump by the way?

Dave