Doing a search using “gerotor, gerorotor, or spur gear oil pump” gives some past threads on the subject.  Here’s a couple of links to past threads.

http://forums.y-blocksforever.com/Topic12065.aspx

http://forums.y-blocksforever.com/Topic8082.aspx

Ted, I read the old thread on the gerotor oil-pump. Have you found any companies that are prducing these pumps yet? I have seen the kits, but no complete pumps as of yet.

Tim.  No companies that I’m aware of is reproducing the gerotor style of oil pump for the Y.  I believe the last company to make a replacement gerorotor pump for the Y was Dynagear.  I’m currently using the Melling gerotor kits to rebuild existing pumps as suitable cores become available.

Lorena, Texas (South of Waco)

I think you have it backwards, the Aluminum one is the "Gertor" pump (bomb) and the rusty Iron one is the "Spur-gear" pump. The aluminum one is favored.

   God Bless.   Tim                           http://yblockguy.com/

350ci Y-Block FED "Elwood", 301ci Y-Block Unibody LSR "Jake", 312ci Y-Block '58 F-100, 338ci Y-Block powered Model A Tudor

tim@yblockguy.com  Visalia, California    Just west of the Sequoias

For oil pump priming, I only recommend using engine oil.  Rotor end play should be 0.002"-0.003", inner rotor to outer rotor clearance should be 0.005"-0.010", rotor to housing clearance should be 0.006"-0.012" and torque specs for the cover itself is 95-100 inch pounds.  Be sure the oil pressure relief valve works freely in its bore.

Thanks Tim for clarifying which pump is which.  Another identifier for gerorotor oil pumps is that they will have flat covers.  Once the covers are removed, the differences become obvious.

Lorena, Texas (South of Waco)