So nobody has any idea huh???
All that I can think of is that maybe its from an old PJS Viper hull or something, but I think that would have used a 550sx style bulkhead mount.
Correct me if im wrong but the js300 used a 550 style pump too? So I dont think it could be from that.
And I dont think it was just machined down because even the hole for removing the impeller is up farther....
Someone has to know!!!!! The mystery continues.