2021-04-06. It has been discovered that some hydraulic lines installed by Altec may be in contact with chassis air brake line(s). Some DOT inspections have considered this to be a violation of federal regulation 49 CFR ยง 393.45 b 2. Over time, chafing of the air brake line(s) could result in loss of air pressure and reduction in braking performance. Altec requires the routing of the hydraulic lines to be inspected no later than the next periodic maintenance interval. The affected unit are some T40P cable placers installed on Ford F750 chassis from May 2015 to January 2020 NHTSA's copy of the document (PDF)
Bulletins from the manufacturer that mention a maintenance schedule or a service interval, as NHTSA summarises them. They are not the schedule itself: read the document, and the owner's manual.
Position 8 of a VIN names the engine on many vehicles: how to read a VIN. Safety equipment depends on the trim, so decode a VIN to see what one vehicle has.