[Redcanuck]

Perhaps the July 1942 Merlin 61 spit could be a converted Mk Vc with the nose of a Mk VIII and the larger radiator under the right(?) wing and the later Merlin 63 spit could be Ranwere's Mk IX Mod.

Here is some info I ran across http://home.epix.net/~cap14/spit9v109g.html