7 1/4 Gear questions (crate 360)

the one thats in the car right now isn't a sure grip but I have another one. both wheels would spin Im not sure if its a sure girp or the gears have been welded I am only 19 but try to soak up as much info as possible, I live in london ky, if you can tell me how to tell if its sure grip I can let you know.