One other bit of info I can tell ya about them is there are 3 types of pumps as far as the inlets and outlets go!
Standing - Both point straight down ! `
Walking - on points down, and one is at about 45* angle !
Running - Both at 45* angles one forward, and the othe back !
I hope this is helpful as the man at Midwest Detroit in Scott City, MO where I buy mine frome always asks what engine? which rotation? and standing,walking, or running? And then replies ya I got it, come get it. Or bring yer old one and I'll build it for you while you go to lunch (depending on whether or not he has a housing or not!) BK