This kit states that it's a P-51C, but what it could be called is a late razorback Mustang with the fin fillet. The presence of this fillet does not necessarily denote a P-51C, and the lack of it does not mean it's a P-51B, either. This kit is pretty much the same thing as the earlier P-51B kit, aside from the addition of the fin fillet. The way Academy did this is by providing separate rear fuselage sections. Unfortunately, they didn't include both sections (with and without fillet) in the kit, so you'll have to know ahead of time which P-51B/C you want to build.