You may not have a low range! I had a 79 CJ-7 when I was a kid. Typically, the quadratrac has a shift lever on the floor if you have 4 Low. The button in the dash is for posi-lock. It's been too many years, I'll let CJ guys tell you more of what you possibly have in your new Jeep. Have fun with your CJ!

94 YJ, SOA, 2-1/2 Alcans, ARB-front, Detroit-Rear, 4.56:1 gears, Oasis Trailhead compressor, 4:1 Terra Lo, 37x12.50x15 SSR's, 8000 lb Ramsey, & etc.