I think 34 is an E-One and I know at least the cab of 21 is HME. And 21 and 54 don't look alike, two different manufacturers (at least the cabs) and 21 has cabinet doors, while 54 has role up doors, so from the doors, I'm assuming that 54 is newer than 21.
I voted for 54
34 IS an E-One & Sawdbuster you're correct on the rest.