66 Power Brake Conversion
 

I just completed a power brake conversion on our 66 this weekend and wanted to share what I learned. I purchased CaptFab's bracket, but to my disappointment ended up not using it. Nothing against the bracket - it is a high quality piece but we were leaving the drum brakes all the way around so it ended up being easier to not use it. I ended up ordering a Z-Bar set up from Summit p/n TFF-4653B and a factory power booster & m/c set up from Oreilly's p/n 50-3535. The brackets that the Summit z-bar comes with space the booster & m/c out too far so I transferred the "Z" mechanism to the brackets that came with the O'reilly's unit. The rod that goes to the brake pedal was still a little short so I used the stock rod with some 3/8-24 threads cut onto the end that originally goes into the manual m/c to connect to the z-bar. I had to cut about 1/4" off the stock rod to make it fit. It is already tapered and the perfect diameter so the 3/8-24 die threads on easily. Two holes needed to be drilled through the firewall since, to my surprise, even though the power booster was ordered for the same year truck I was working on only 2 holes of the original 4 line up. I couldn't be happier with this set-up! I replaced ALL the brake components (drums, wheel cylinders, hoses, shoes, hardware) and this truck stops as good as my other trucks with disc's in the front.
I am sure this has been posted before, but I couldn't find it anywhere and spent a lot of time looking for the right parts to make this seemingly easy swap work.

Re: 66 Power Brake Conversion
 

With my booster bracket and drum/drum brakes all you would need to do is bolt up a '67-'70 truck booster and master cylinder. Then all you have to do is lengthen the booster pushrod.

Re: 66 Power Brake Conversion
 

I had the guys at the auto parts store pull boosters for a few different generations and all either were disc/drum set ups or had dual pot drum/drum M/C's. I even found the original thread where someone recommended an early 70's Buick Estate wagon drum/drum set up, but it was a dual pot. I know I could have "Y"d them together or ran separate lines, but I didn't want to do that. I elongated the holes on your bracket to accept the 66 booster and loved the way that looked (nice and tight to the firewall), but finding a way to elongate the rod meant either having to cut and weld a new one or having 2 pivot points on a straight rod which I didn't feel comfortable with. The 66 booster just has a short rod with an eyelet at the end. If it was a threaded fitting there would be many more options.
I know there's a dozen ways to skin a cat I just personally found for retaining the drum brakes, but adding some assist, this way was the easiest. Knowing what I know now it can be done in a couple hours or less too.

Edit: I know I could have swapped out one of the dual pot M/C's for a single and that was going to be option B if this one didn't work as planned.