funny you post this as i have had the same problem recently...i have a rb20 in my s13, installed a rb25 turbo, run fine, till i blew it (due to stupid reasons dw), so i looked at putting an rb20 turbo on as they cheap as chips n i only want it for a run around now. I had one from a makes car..fitting it up fine then realised it had a faulty exhuast wheel, btw this turbo came of a 93 modle r32gts-t. So i bought one the other night from a forum, was a rb20 turbo, so i went to install this and realised the water feed and return lines are different! there are slightly smaller. So i rang nissan today they said possibly it was an older model one? $75.00 each of the lines (feed/return) so i opted out there. went to a mobile auto hose guy he provided me the right side banjo bolts and fittings which i used to fit up cutting the original hosing and inserted rubber and clamped. she all good now!! Hame
p.s sorry for the book of a post.