on 505 the original was a Henderson Mark V. At least that is what I replaced last year. I had seen some of the black plastic pumps from 30 years ago showing some cracking and didn't have easy access to a rebuild kit ... so just grabbed a near by WM Gusher low end. But even then they had to order the thru deck version. And they carried the rebuild kits for that gusher.
The Henderson is clearly marked.
I replaced some completely "unmarked" pumps on other boats last year and they did seem to be old Gushers... naturally with no indication of the rebuld kit and no hint if a new kit would rehab an old pump.
