Rwy in sight,
Boeing has customer numbers that have remained constant for many years,
Qantas was 38.
PanAm 21
BOAC 36 (I think this one goes back to the Stratocruiser)
The original Continental (I think) 23
TWA 31 etc.
Thus, a Qantas B707-320C was a B707-338C, all the way through to the B767-238/338 and B747-238/338/438.
As I recall, one of the ex-Qantas B767-238 has wound up in Africa somewhere.