Hi, I'm looking for a working oil pump for my DT 175 1975. I have read somewhere that an oil pump for an RT 180 from the early 90's should work but am unsure if this is true, therefore primarily looking for an original pump for my motorcycle.

1976 DT175C has the same pump as the RT180, not 1975.  It's been a long time since I researched but from memory the worm drive gear ratio changed on the DT175 between 1975 and 1976?  

While the 1976 might look similar to the 1975, the 1976 DT175 has some fairly significant differences...  things like the frame, tank, and many internal engine parts were changed. 

DEET might be able to help you with a pump.

Ok, thanks!