I guess back then pretty much everything was an option, even on the supposedly top-tier muscle cars.

Its funny, because all of the ones (just 2 others) that I have seen in person have had drums...

Just did a quick search on the net to make sure that we arent crazy, and found a few others.

http://www.moparmusclemagazine.com/featuredvehicles/b_body/1970_dodge_coronet_rt/index.html