Using the bill of material number, you can find part numbers in the Dana book for practically every axle component between the steering knuckles. That includes spindles, bearings, seals, most (but not all) knuckles, differential gears, cases, and bearings. But the number doesn't indicate whether the axles had drum brakes or discs. Those were added later by GM. According to GM parts sources, front 44 discs were made standard in 1971, and we know that all '73-and-up 44s have discs.