A friend of mine has a 77 NYB 2 door (61,000 miles) with the self-leveling rear suspension system. Every thing appears to be in tact but the rear original shocks are looking somewhat aged. If they need replaced can we install regular air shocks in their place? Tomorrow we are going to adjust the self leveling mechanism and see what happens......there are no leaks in this system anywhere so it should do what it was intended to do.