I recently purchased a athearn sd50 what I believe is a rtr model and it is not working. The whole chassis is intact with trucks and motor and shell is in need of some TLC. I got lucky and purchased a new KCS sd50 shell basically new condition with the gas tank as well will be in its original rtr yellow box. the seller only needed the chassis off of it. Now I have a good chassis and shell but want to try and retrofit a newer genesis motor and possibly upgrade the trucks. if any one has done any similar work and would be kind to shed some light on this subject id greatly appreciated.