John, yes the ride height can be adjusted, easily. I believe spartan uses 1 valve at the rear and one on each front wheel. My suggestion is to call Spartan and they can give you the recommended ride heights for the rear and for each front corner. There are a dozen threads in these forums (and others) on how to perform the adjustment once you have the correct numbers from Spartan.
Might I also suggest replacing the "whiskers" while you're doing all this - at 12 yrs old, it wouldn't be a bad idea for peace of mind - considering each kit costs less than $30.00. See my thread on replacement of them here: http://www.irv2.com/forums/f25/air-r...age-70924.html