9" vs 10" drum brake spindle question

And SSBC is still very much in business and providing parts.
The SSBC now in business is version 2.0. They bought the OG SSBC's assets out of receivership for pennies on the dollar, and are doing some of the work SSBC v1.0 did. A few years before the new SSBC opened a few miles away from the original location, the original company went teats up, leaving customers, vendors and employees empty handed, owing for paid orders, receivables and wages, respectively. At that time, the rotors in their Mopar A-Body kits were proprietary, and I'm having trouble believing the Ford rotors fit the Mopar A-Body drum knuckles without modification. My friend paid for a pair of SSBC rotors and six weeks later SSBC shut their doors without shipping them. He ended up converting his SSBC conversion to brakes from a '74 Duster. He spent a lot of money on parts that he ended up junking.

The lesson? Buy stock-based systems like those sold by Doctor Diff or from an aftermarket company like Wilwood. Or take your chances at being left high and dry.