A quick Google search came up with this: Early GX-3 bodies are threaded 9/16"-18. The standard 2K threads are 9/16"-24. It was suggested the body could be re-tapped to 9/16"-24 without issue. Seems a little hacky to me.
Compare the pump kit to the original banjo bolt if possible.
I'm not 51, I'm 18 with 33 years of experience!
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