Rear Brake Cylinder

I have a 1990 XJ with the Dana 35 without ABS and I am going to be replacing a rear wheel cylinder tommorrow and need to get the replacement wheel cylinder tonight. The only problem is that the part stores list two different cylinders. One that is 3/4" Diameter Cylinder Bore and one that is 13/16" Diameter Wheel Cylinder Bore. This is the ony car I have so I cant take off the cylinder and just take it in for comparison, so how do i find out which one I need? Anybody know off hand? Thanks in advance for the help, I really appreciate it.

I don't have a '90 FSM but the '88 FSM lists the rear wheel cylinder as 0.875" diameter. That's 7/8" -- bigger than either of the choices you were offered.

However, the same spec table lists both the 1-3/4" and 2-1/2" width shoes, but no mention of different wheel cylinders. And I'm about 98% certain that the D44 axle used a different wheel cylinder.

Sorry -- I think I've offered more confusion than assistance.

I am 99% sure that the smaller diameter wheel cylinder is for ABS but, can't find my docs. Search on the Internet, and you will come up with the 2 different part numbers to bring to them for reference.

buy both then take back the one you dont use