If it's a stock transmission, it'll have the cast drum in it. OEM always cast, as it was cheaper to build.
Also, cast drums typically only had 3 sometimes 4 friction plates in them.
Can't speak for the hemi-drum though as they're as scarce as hen's teeth. Maybe someone who has an oem hemi drum can tell you how many frictions in a non-modified strock drum.
Some aftermarket steel drums can now accomodate 6 friction plates.
For the hard core racer looking to shave weight in the trans., there are also aluminum drums available. Never recommended for the street though, too high a maintenace item.