Does GVWR determine rear drum brake size?

[jlmnjem]

I'm trying to solve a brake pedal height issue (it sits too high) and I suspect the master cylinder push rod is too long. I think replacing the master cylinder with one that is supplied with a shorter push rod will solve the problem, but MC selection is based on rear drum size. The options are 10"x1-1/2" or 11"x2". I've measured my rear drum and it appears to be the larger drum, but what determined which size drum was installed. I suspect it's GVWR, as my VIN decodes to 4150 GVWR, but I'd like to hear from someone who knows for sure.

 

[Torxhead]

There are adjustable push rods available, I got one from one of the big box 4wd outfits. To increase you Jeeps braking ability try one of the aftermarket brake boosters or one from a YJ:https://collinsbrosjeep.com/76-86-cj-power-brake-conversion-kit/