I replaced the front drums on my 442 years ago, and one hub was aftermarket, as, on the same drums, one simply holds the drum against the hub and the wheel held on by the bolts holds it on, and the other has these little splined ledges that, when you bolt it down the first time, press fits into the drum lug holes, then the hub and the drum because one unit and you have to pull the bearings to check the brakes.

About the only thing I could think of for this is eliminating any non-concentric slop from the drum being a little loose around the hub lug studs, or keeping the drum from possibly falling off when you are changing a tire.

Seems like it's a pain in the bohunkus for not much benefit.

 

Someone installed the wrong studs. The studs with the serrations beyond the hub, are intended for brake drums that are permanently mounted to the hub, as in many of the full sized cars of the 1950's & 1960's. Once the hub was pressed onto the drum, there was a swaging tool that would press a metal to metal attachment so the drum couldn't come loose. Back in the day, once the drum was mounted to the hub, you would install the drum & hub assembly on a brake lathe, and take a cut to true the drum to the hub. My 1966 Pontiac was made like that, and when doing a brake job, you would measure the inside diameter of the drum, and then using a brake shoe arcing machine, grind the surface of the shoes for a perfect fit to the drum. It was a good system, except for the asbestos that was released in the grinding of the brake shoes. Occasionally, I do see the arcing machines for sale, but everyone today is afraid to use it, because of the brake shoe dust that it creates, even though asbestos has been removed from all modern brake lining materials.

 

Ah Hah! The riddle is solved. Thank you. I do have a disc setup that will go on the car, so all this will be rendered academic in the restoration.

That arcing machine sounds awesome. Nothing like custom fit. Reminds me of an on-the-car tire balancer and shaver.