Oh, okay. I thought all of the 73 up cars were front disc. If I came up with a 73 up disc set up, I figure original OEM would be pricey. I don't need original, this car is far from it. lol
Maybe they're lighter than factory type discs? I don't know how to find the weights.
But mostly, I figure it'd easier to do, not having to scare up parts from different cars. Junkyards are rare around here. Also, I'd bet that someone who put front discs on would just about give away the drum set up.
One reason I'm not afraid of drums (other than they're probably cheaper lol):
A partner and I raced a 3900# Road Runner in Stock Eliminator. It had 10" brakes because it was a Satellite that we cloned. Aftermarket discs weren't legal at the time, and factory discs were considered to drag. Anyway, we stopped that from 116 mph with no problems.
Hell, I'd probably use the 9" with an adjustable proportioning valve (Assuming they wouldn't get along with the GM 9 1/2 rear drums. Long story.) if I could make them BBP. hmmm...