the rear disc brake kits or brackets are often sold or advertised that you can use a "Cadillac caliper with parking brake".
In reality those calipers are expensive, or hard to find cores for them, and I've seen it mentioned several places that they're not the most effective parking brakes.
Which means if you don't have parking brake on the back of the transmission then converting to rear disc with those brackets might not be the best option.
