Yes your correct it is drywall over a 2x4 structure covered with 3/4" particleboard. I have two of them, they used to bolt together to build full scale airplanes on. I am past that and only build models now though. Overall I have been pleased with the NP .40 kit. It is safe to say that the more expensive ARFs are most diffinately of much higher quality though. I am sure the customer service is much better as well. No luck on getting the wheel well liners replaced, had a few folks contact me but looks like I will just build them out of balsa. Their customer service needs work to say the least. I am glad my kit did not have a major defect. Retracts are pretty much not worth installing. I purchased .40 sized Hobbico mechanical retracts and they are of much higher quality. I also purchased the metal gear HD servo, save your money on that one.

This build took a second seat to a design contest bird over in the 1/2a forum. I have to complete it by Halloween including flying. So most likely will finish the Mustang after that. More to come.