[vectorit]

I'm taking a wild guess here, and hopefully some one else will chime in.

In my case, it didn't really matter the bore size. What did matter, was the position of the inlet for the brake line.

Best bet would be to take out the old one, and head over to a Napa store since they tended to have them in stock in my case. Then compare yours to what their puter is telling them to sell you.

I went through a couple of purchases before I got the right ones, and that's because I didn't bring in my original ones. Those things get changed out so often over the years, that what you have in there may be completely different from what it came with.

Oh, and I checked my "big book" to see if there was any references to the bore size of a wheel cylinder and there were none made. Though, my book is for a 68. Not that that should really matter, since they are so much alike.

Good luck!

Oh, and take this opportunity to replace your rubber brake lines if they are old! Takes nothing to replace them, except for a few extra bucks and a whole lot more piece of mind. Also, flush out ALL of the old fluid. Otherwise you will be doing this again sooner than later, since the old fluid is probably full of contaminates, grit, and water.