Jaybo, for an engine mount I used a Dave Brown type. I had to install two different T nuts in the firewall but it was worth it. I didn't want to use the aluminum mount to put my O.S. 70 on. Also I just used the stock tank and haven't had any problems at all. As far as the nylon bolts on the landing gear, I've seen guys at our field have bad luck with them. They break off alright but the landing gear then tends to fly up through the wing or into the tail stabilizer. Mine are steel bolts and I haven't had any problems with them or the landing gear block