My Toter is on a 1989 FLD120 chassis. The truck started life as a twin screw road tractor. It was stretched out and converted to single axle. It has Freightliner 2 bag air ride. The truck only raises about 1.25" when the suspension is aired up. I suspect that it does not have enough travel. I can make adjustments to the ride height but I do not know what the proper spec is. How high should the suspension be?