The shape of the door says it's not a model 1, the long rib tails for the flaperons say it's not a model 4. Lift strut length is different on model 2 (98") to model 3 (about 109"). If the original poster has a tape measure, he should be able to know what he has. Also, I'm not sure if the serial number was stamped on the early (pre model 4) models. If the N number was available, we could also check what the FAA says it is. JImChuk