If the left side is lower it isn't because of the slides, but probably due to ride height adjustment being off. There is a Neway Suspension Service Manual under Chassis & Brakes on the Alpine Coach Assoc. Tech Page
that tells how to adjust the ride height. If you search ("find") on ride height on this forum you will find the correct adjustment height in several of the threads.
If you are not up to doing the adjustment yourself, you can have it done at any truck shop that does suspension, Cummins Coach Care location, probably most Freightliner shops, etc. If doing it yourself, observe good safety precautions when crawling under the coach; several Alpiners have made this adjustment themselves.