The Mrerlin was built in many variants, some being applicable to only one aircraft type, see NOTE (2) regarding allocation of Mark numbers.
Commercial Merlin versions. Some warbird operators are fitting commercial Merlins because of their beefed up components.
Merlin 500 series: Two Speed - Single Stage Supercharger
Identical to Merlin T24-2 but termed Merlin 500 for Civil or Commercial operator
500 B.O.A.C. Lancastrian York
500-2 B.S.A.A. Lancastrian York
500-3 Alitalia Lancastrian
500-4 Skyways Limited Lancastrian York
500-5 F.A.M.A. Lancastrian York
500-6 Silver City Airways Lancastrian
500-20 Fiat G.59
500-21 Flight Re-Fuelling Ltd Lancastrian
500-23 Egyptian Government Lancastrian
500-29 CASA C.2111
500-45 Hispano HA-1112
501 T.C.A. Lancastrian
502
502-1 B.O.A.C. York
504 No Production
530 No Production
539 No Production
549 No Production
Merlin 600 series: Two Speed - Two Stage Supercharger
600 Tudor Prototype (Converted to Merlin 102A)
604 Argentine Government
620 T.C.A. & RCAF D.C.4 M.1
621-1 B.O.A.C. Tudor II
621-2 B.S.A.A. Tudor II, IV, V
621-5 Flota Aerea Mercante Tudor
621-15 Argentine Government Lincoln
622 T.C.A. (Domestic) D.C.4 M.2
623-2 B.S.A.A. Tudor IV
624-10 T.C.A. (Atlantic) D.C.4 M.2
625 No Production
626-1 B.O.A.C. Canadair IV C.4
626-12 Canadian Pacific Canadair IV C.4
630 No Production
631 No Production
640 No Production
641 No Production
Merlin 700 series: Two Speed - Two Stage Supercharger
724-1 B.O.A.C. Similar to Merlin 626-1 with cooling mod.
724-1C B.O.A.C. As Merlin 724-1 with crossover exhaust
722-10 Canadair As Merlin 622-10 with cooling mod.
724-10 Canadair As Merlin 624-10 with cooling mod.
Source: Rolls-Royce Production Drawing Office, February 1953.