AS400 Trucking, TMS and Logistics Software

Should fleet maintenance run in the same system as dispatch, or separately?

Either can work, but you need to know which one you actually have before evaluating new software. Some IBM i products handle dispatch and fleet maintenance as one integrated system; others treat them as separate products that share data. Map which system owns vehicle maintenance history and utilization data today before comparing vendors, so you can evaluate integration claims accurately instead of assuming a single-system answer.