We have oil leaks in our shocks and the folks at Cummins where we have the coach serviced said they need replacement. REV parts says that based on my VIN we need two different Bilstein shocks -- four for the rear and four for the front. The guys at Cummins say the ones for the front are shorter than what is currently installed and recommend using the same shocks front and back. I guess it is possible a previous owner replaced the shocks and did not use the correct parts. Any thoughts?