There's a guy in Kauai that cooks chicken using some "less than 55 gallon drums". I asked if I could look inside to see if and how it differed from a UDS. I saw three slots for the cooking rods, and NO fire basket. Without having looked inside of a PBC, my guess is that the fire basket is the only difference.
My guesstimate for the amount of charcoal/wood in there was this:
1 1/2 Weber chimneys of charcoal and and 8" by 3" piece of wood.
Dbl Bbl Smoker, UDS, ECB, Char-Broil gas grill & charcoal grills, SJ - Certified Moink Baller