When we bought our 98 Spartan DSDP 1.5yrs ago, the ride height was set very low both frt and rear, and there was a bad vibration coming from the rear of the vehicle. When I crawled under it, I could see that the driveshaft angles were too great and that raising the ride height would help. So I raised it some, but I didn't know what to set it at exactly. Immediately most of the vibration went away. Recently decided to have the balance of the driveshaft checked. It needed balancing, but was otherwise in good condition. More vibration gone!
Recently we found a truck shop($75/hr) that has a computerized Hunter alignment machine that would aligned both axles($209) on our Spartan chassis if I set the ride height before I took it to them. They do the local city fire trucks. I set the ride height to factory specs,and now all the vibration is GONE!
I really didn't have a problem with the steering, I just wanted it checked since its 12 yrs old w/73K miles and I have no record of it ever being aligned since new and the lower ball joints boots are trash.
The ball joints were tight and the frt alignment didn't need adjustment. The rear axle was 1/8" out, so they set it back to 0". It still drives great!
I have to mention that the technician told me that his boss generally wouldn't let him align motorhomes
because the ride heights were usually way off and needed substantial adjustment(time & $$$$) before the alignment could be done. Since I told him I would have it set correctly, they agreed to work on it.
Since the frt end didn't need any adjustment, they only charged me for a single axle alignment($150).