Thanks gents,
From what I understand the 1c had the smaller paddle blade prop, whereas the prop on the TBM 3 was similar to that used by the F4U 1d, 13.1" in diameter I believe. I have two kits to build and both will be in FAA livery, one for the Pacific Fleet and the other for ops during D-Day period, but not sure if it is a 1c because of the designation of Avenger Mk 1 and it's coincidence with the Grumman designation.
Cheers