I purchased a 1972 Coronet Custom and popped the front tires off and found a normal drum(8788) on the passenger side but on the drivers side I found a heavy rear wheel drum(type with ridges on side of the drum) is there a reason they did???

 

Probably just had the parts to keep it going.

 

That's what I was thinking but it always good to ask first just in there an actual reason for it!
Thank you