Today I rebuilt the rear master cylinder. The challenges you run into are not always what you anticipated. I used a KL kit which is commonly listed. I had 3 issues with this kit.
1) It omits the O ring for the reservoir adapter.
2) The seal on the piston does not come pre installed.
3) The accordion boot finish is a white chalky faded finish. My 35 yr old original looked better.
This may not sound like a big deal, but just try installing the piston seal on the piston. The seal has be stretched 400% over the piston land - impossible without damaging it. After 2 tries, I built a seal install tool using the tip of a caulking tube. By carefully sizing it to snap over the piston, I was able to slide the seal down the install tool and get it up and over the piston land. I consider this very weak from these kits. But since it's the only game in town - we find ways to make it work.
The housing was then cleaned up, primed/painted/sealed. I used Forever Black to put some permanent color on the new boot seal. I polished up the passenger foot rest plate and bolted it all together. After scrutinizing the reservoir hose internally, I decided that will be replaced with an aftermarket bulk hose. Way to many crystals and garbage inside to keep.