[bestgenman]

At one time I had an 89 which is pretty similar to yours (40' with tag axle).  The drive and steer springs were the same,  WO1-358-9447.   That is a Firestone number with a 1" NPT opening for the air line.  I concur with @rheavn on the Firestone download to be certain.  Likely will have to be ordered as I did not find any in stock.  I do have a spare of that number since my 2000 uses four for the drive axle.  If you need it asap, I'll send it to you and you can replace it or pay me up front.  text me @ 614-271-7488 with your number and i'll send you a picture.