I have a 1998 Jeep TJ that I just bought for my son with 77k original miles. Everything is great except this temperature control knob is missing. To slide it with your fingers hurts like hell. I can't find the knob anywhere on the internet, I can buy the whole unit on ebay but I'm not spending $100+ for a little knob. Anyone know where to find one? If not, is it possible to retro fit the 1999 rotary style control unit into the 1998?