Engine identification

Hi - my son has a 1979 109. The original Series 111 petrol engine was replaced by a 2.5 diesel engine, a 15J (Sherpa engine we think) but that too has now been replaced by another engine, 2.25 litre we think. We are having difficulty identifying the engine type as the servo pump is bolted onto the engine over where the engine number is.
Can anyone identify it from the two attached photos? Having hopefully identified it we can get hold of an appropriate manual.
Cheers

Landy 2.25 diesel. Can't see if it 3 or 5MB (5MB has a lot more webs cast into the main block than the 3MB).

HTH

Cheers