It's difficult to tell in a photo. I'm guessing it's a B2 if that is the original wing with the B2 stickers on it. Also the white plastic C hub carriers are not original parts. Possibly modified from an original RC10 or RC10T. The only two significant change made from the B2 to B3 was the suspension arms. On the B3 the arms are all the same length from hinge pin to hinge pin. I also believe the rear shock tower was slightly lower on the B3.