I bought an older ('95 - '98) John deere stx 38 lawn tractor. It has a black deck and a Kohler 13 HP engine on it. When you turn sharply, the left front tire rubs against the deck, this would be the left side as you sit on it. Could the linkage be wrong length?

I have a STX38 about the same age as yours and it is a good mower.
Am guessing someone has put the wrong front linkage on it or has installed them wrong. This also probably means it has the wrong belt on it.
Check your left front axle for excessive slop, maybe the wheel is coming back to far.