I'm currently fying a TT III built in the late 1980's. I flew pattern in Texas during the seventies and sporadically in the 1980's. The Southern R/C Tiger Tail and Bootlegger fuses were blue polyester w/out gel coat. They included a glass floor for the pipe compartment if you chose to use a rear exhaust engine and run the pipe internally. The poly fuses from Southern were light, but not as nice as a well-done epoxy glass fuse. The polyester glass tends to be more brittle and crack at stress points, etc.