How long do Billstien shocks last? My tire guy said to expect 70K but I have to travel down a freeway where the expansion joints are the same length as the wheel base. This causes the truck to bounce no matter what speed I run. (Although it is much worse at some speeds. ) The shocks seem to be getting a little soft. I only get 30K miles from the OEM's. I am coming up at about 40K for the Billstiens.