[NO LIFT]

New batteries.

Batteries in medium and heavy duty trucks are susceptible to vibration since most are located in a box that is attached outside the frame rail. Vibration is bad for battery life. A piece of rubber mudflap under the batteries is common.

Trucks these days have a great deal of electrical items, ECM's for the engine, brake ABS, even the turn signals.

Your shop will probably have several operators that need batteries this time of year...and go ahead and replace all of them!