9in drum brakes
The small bolt pattern, A-body only drum brake parts are not always easy to find, and are not always inexpensive either. I’m not sure what the current status is for availability but the drums and other parts have dropped out of production more than once in the past.
The 9” and 10” drum brake hubs are not reproduced at all, so you must remove the hubs from the drums to replace the drums. If you need hubs, you have to source good used originals.
The wheel bearings on the pre ‘73 drum hubs were small, so overheating and galling can occur is they’re not maintained really well. All the ‘73+ stuff used larger wheel bearings, including the ‘73+ drums. The earlier drum spindles also use 1/2” bolts to hold the lower ball joint on, so, the entire weight of the front of the car is suspended by 4, 1/2” bolts in shear. The KH disks used 9/16” bolts for that purpose, the later 73+ disk and drum spindles used 5/8” diameter bolts for the same job.
I had 10” drums on my ‘71 GT, I replaced them with disks. The disks are far superior. I wouldn’t use 9” drums on anything that was going to see more than infrequent street use.