I have a 1980 c10 i am about to buy a dual exhaust kit to help my engine breath a little easier but the kit i am wanting to buy says it fits 1973-1977 2wd i need to know if thats because its just not compatable or just because the kit doesnt include catalytic converters and stock my year model had one. I didnt think there had been an exhaust system change from 77-80 besides the catalytic converter. Would the kit therefore be compatable with my truck?