Andy, being an SR20 you have in the car you should be able to just get a 200sx or Skyline master cylinder depending on what gearbox you have.My 63a box with its slave also firts a bluebird L series 63 series box and also my RB gearbox as well.

Hey guys, my clutch master cylinder started leaking internally a few days ago. I've found a new replacement, but I'm wondering what others might work or be the same master cylinder. It seems all the Nissans use a 5/8" cylinder, even the stock 1200 one. From what I can see it looks like a B210, 510, 240Z, 260Z all have the same bolt pattern for the Master cylinder, only the pushrod length is probably different. Seeing as how they're all 5/8" the hole for the center section through the firewall should be the same on all of them as well.

I ask because I called around the parts stores looking for a new one and out of about 8 stores, the best I could get is a repair kit. I could probably get away with just doing a repair kit unless the inner bore of the aluminum body is worn out too much. I magically found a whole new master cyl. on Ebay and bought that, but resources like that are sometimes hard to come by, I just got lucky.

I'll replace the old one for now and buy a repair kit to try to fix it as a spare since they seem to be hard to get...but if the other Datsuns can swap in, then I won't worry about it.