[Mook]

I just picked up a rebuilt 3:23 posi that I will be installing into my stock 69 GTO. The car had a one leg 3:08 in it, I was thinking while I'm making the switch would it worth the extra work and $$ to put disc brakes on the rear......if so how much $ would it set me back and how much extra work is involved? thanks

[77 TRASHCAN]

There are a lot of folks that make rear disc kits.
Some do not have provisions for the emergency brakes (cables), be sure to ask about this.
The rear discs will help some, but the fronts being disc are 10 times better than front drums.

I believe the stock front discs to be VERY good brakes to start with, most want to sell you the latest super trick stuff, I don't believe you need them. The front disc pads use a standard industry part number of D52, you can use a D153 pad in place, it has a little more surface are of friction material, and does help some, in my opinion.

You might ask who ever you call about a front And rear kit and how much. Beware that some of the new whoop a$$ brakes on the market have to have bigger wheels for clearance.
I helped my brother install a rear disc setup on his 73 camaro, using the stock front brakes. I was not pleased with the setup, but it does work (I will not say who's parts they are)

Baer Brakes seems to have the best stuff, I don't see them advertise in magazines
much, but, I'd try to call them first. I believe they have several different ways to go.

You will have to use a different master cylinder, change some rear lines/or fittings on the rear, and change some fittings or lines to the master cylinder, if you add the rear disc setup.

I would just re-build the stock stuff you have, it WILL stop good and not cost mega $$$ and all the hours getting the new stuff to work..........................