On my recent auction purchase D4 7U 22xxx I drained oil and water out of steering clutch compartment, flushed with gas, changed oil and transmission fluid and got everything working good. The first time I put it to work the oil cooler started out to leak. 

I have bypassed these before. I understand if this plug is removed, a spring and plunger can be removed and the inlet and outlet ports can be plugged. Matching the threads in the ports is always a problem, they are close to 3/4" not but are not tapered. I am afraid if tapered pipe plugs are used it could crack the casting.

I recall Old Magnet mentioned a source for proper plugs for these ports. Could you tell me where I could get them?

Thank you,
Tom Armstrong

The plug is to drain the filter housing, the cap with two bolts contains the spring and plunger. The plugs and gaskets for the housing are 2-6B2731 Plug and 2-8B3410 Gasket, from Cat.

I use -10 size  0-ring face seal plugs (hydraulic fittings) which are a 1" - 14 tpi straight thread and  bit of sealer.
They only run a couple of bucks each.