adjusting brakes question

That is tough. A lot can change in 36 years, or have been changed and look factory.
The first time I recall running into something like that was in 1987. It was the steer axle brakes on a 1984 4300. It had new steer axle shoes and drums put on it and was parked in the lot. Driver came back because it shook badly with brake application. It was a company truck and nothing had been changed on it. Old drums were all ready gone in the trash so nothing to compare it to. They ordered new ones from the dealer. They also did not center on the studs or the hub.

 

I got to looking at the drum on the other side. Here it is:

 

Web 66895 that is your number those are great.
I have seen some off shore drums out of balance so bad you could put them on a concrete floor. Then take you hand off and they would roll back and forth like a back window bobble head dole. Machine work likely matches.

 

To be clear, the drum is off. Is the position of the cam in the pics with brakes set, or brakes released?

And you're still fighting the spin,bind?

 

Still fighting the drag, spin?