I have a 1972-73 made slant six which has a pretty steady leak out of the body of the oil pump. I have a new gasket, but the housing is REALLY stuck on there. I am afraid to break something, particularly the aluminum section between the outer cover and the block. Any suggestions to getting this done without getting out a hammer? I am hesitant on using heat, but I will do what I have to do. Any advice is appreciated

Are you sure the pump body is aluminum?
Most later pumps are cast iron.
I would think a sharp wrap with a dead blow should break it loose on the block.
Make sure you have all 6 bolts out.
Later pumps are 5 bolt, but older ones have 6 bolts.

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Hyper_pak

Be sure you get all 6 bolts removed.

First use a twisting action to break-loose the pump from the engine block.
Removing the oil filter and placing a block of wood on the filter's gasket sealing surface, then lightly strike the wooden block.
If the gasket was glued-on, rotation will likely tear the gasket in two.
Pry outward once the pump breaks free and rotates.
DD

I'll give it a twist and a shot with a dead blow mallet. I have all the bolts out. I wonder if my unit is different since it is an industrial slant on a John Deere machine.

You may also have to jack the engine up to get it out.

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63 Plymouth Valiant Wagon

hard to say. He did say it's on a John Deere something or other.... most farm stuff I see is more wide open, than a car chassis.

It is wide open, it can get to it no problem.

I have a NOS 6 bolt aluminium oil pump in a slant. I had cracks in the arm carrying the filter. Cracks were not visible from the new pump. I did several running cycles with brake cleaner washes in between and then followed from where the oil came out. During the preheat before MIG welding it was easier to find cracks as the smoky oil presented those cracks well. It came good enough after welding.

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1966 Dart. 170 cu.in. 200 rwhp.