Sorry. I haven't used a tremolo in 20 years and I know little about them. If my info is correct and the tremolo is original, it should be the licensed Floyd JT580. Quality opinions I've read are varied. If your not going to use it I suggest blocking it with a block of wood or getting something along the lines of a Tremol No. Info on both methods is easily found online. This will essentially "hardtail" your guitar but it can easily be reversed.
Thanks. The guy I am buying it from never used it so it should be the JT580. It's near mint condition AND he's giving it to me for £75 ($120ish)