What chassis? Workhorse has problems with brakes. Recall is in effect. If rig is on recall list it should be done immediately.
Some years of Ford has problems with the spark plugs seizing on removal and breaking off. First plug change should be done by dealer which I do not care for.
Have them check to see if there is maintenance records available.
I have had good luck with my Fleetwood product.
Bud
USAF Retired
Pace Arrow
2003 Chev Ice Road Tracker