That cant be right.
P-51C
Packard Merlin,V-1650-7,1,490 hp,Two stage supercharged
P-51B
Packard Merlin V-1650-3/7,1380 hp.or 1,420hp Two stage supercharged.
All in total they travel almost same speed but.Just would be nice to intro all 51's to AH.
With the introduction of the P-51C-5-NT onto the Dallas production line and the P-51B-15-NA in the Inglewood production line, the Packard V-1560-7 engine was adopted as standard.
Serial numbers of P-51Bs:
43-12093/12492      North American P-51B-1-NA Mustang (NA-102)  c/n 102024541/24940.  400 aircraft
43-6313/7112       North American P-51B-5-NA Mustang (NA-104)  c/n 104-22816/23305, 24431/24540, 24941/25140. 800 aircraft
43-7113/7202       North American P-51B-10-NA Mustang (NA-104) c/n 104-25141/25230.  90 aircraft
42-106429/106540      North American P-51B-10-NA Mustang (NA-104) c/n 104-25231/25342.  112 aircraft
42-106541/106738      North American P-51B-10-NA Mustang (NA-104) c/n 104-25343/25540.  198 aircraft
42-106739/106978      North American P-51B-15-NA Mustang (NA-104) c/n 104-25541/25780.  240 aircraft
43-24752/24901      North American P-51B-15-NA Mustang (NA-104) c/n 104-25781/25930.  150 aircraft   total of 1990 P-51Bs
Serial numbers of P-51Cs: 
42-102979/103328      North American P-51C-1-NT Mustang (NA-103) c/n 103-22416/22765.  350 aircraft
42-103329/103778      North American P-51C-5-NT Mustang (NA-103) c/n 103-22766/22815, 03-25933/26332. 450 aircraft
42-103779/103978      North American P-51C-10-NT Mustang (NA-103) c/n 103-26333/26532.  200 aircraft
43-24902/25251      North American P-51C-10-NT Mustang (NA-103) c/n 103-26533/26882.  350 aircraft
44-10753/10782      North American P-51C-10-NT Mustang (NA-111) c/n 111-28886/28915.  30 aircraft
44-10783/10817      North American P-51C-11-NT Mustang (NA-111) c/n 111-28916/28950.  35 aircraft
44-10818/10852      North American P-51C-10-NT Mustang (NA-111) c/n 111-28951/28985.  35 aircraft
44-10853/10858      North American P-51C-11-NT Mustang (NA-111) c/n 111-28986/28991.  6 aircraft
44-10859/11036       North American P-51C-10-NT Mustang (NA-111) c/n 111-28992/29169.  178 aircraft
44-11037/11122       North American P-51C-11-NT Mustang (NA-111) c/n 111-29170/29255.  86 aircraft
44-11123/11152       North American P-51C-10-NT Mustang (NA-111) c/n 111-29256/29285.  30 aircraft   total of 1750 aircraft