Engine rebuild: Oil Non-return valve?

[rob_e30]

So the Bentley manual as well as Real OEM show a "Non-return valve" in the engine block (http://www.realoem.com/bmw/showparts.do?model=AF93&mospid=47305&btnr=11_1960&hg=11&fg=10) but I have a few problems:

1) I took the engine apart and do not recall this part being there.  I looked at the pics I took as I removed the head and it's not there.

2) I bought a replacement sleeve and check valve and it does not fit in the block.  The space where it would recess into on the head is not large enough to accept the stack either.

Has anyone seen this before or rebuilt an M42 and have a recommendation?

[2002maniac]

it was added in 92 or something.

Not needed for our cars.

[Shocker]

It keeps the oil up in the valve train longer.