To my knowledge, the Hilborn PG150 pump had four "revisions" over the years; PG150, PG150A, PG150B, PG150C, and PG150D. The D pump is the latest/last and had a billet body, and the others were cast.
What are the differences in the first four versions?
Also, did all versions have the same submodels; -00, -0, S0, -1/2, and -1?
