One of the things I needed to do for the Trail Boss was to fix the fuel leak at the gas tank. I got new fuel lines near the beginning of my work on it, and later on I noticed it was leaking fuel at the petcock valve area. I thought maybe the fuel line was not attached securely so I ignored while I was working with the new carburetor. Later on, I realized it was actually leaking at the valve where the handle turns to determine if the tank is on, on reserve, or off.
I researched a while and decided to take a risk and try the cheap valve from Amazon. I didn’t figure it would work with the Trail Boss’ reserve switch extender (it doesn’t), but you can still reach the valve itself to turn the switch. This is the valve I bought: https://amzn.to/2UbARDF. It works great on a 1994 Polaris Trail Boss 250.