What service records should you ask for before buying a diesel truck?

Ask for records that prove the truck was maintained, not just cleaned up for sale. Start with oil changes, fuel filters, air filters, coolant service, transmission service, differential service, transfer case service, brake work, tire records, battery replacement, and alignment or front-end repairs. On newer diesels, ask for EGR, DPF, DEF, NOx sensor, regen, and emissions-system repair history. For engine-specific trucks, ask about known risk areas. Injectors, fuel pumps, turbo work, head gaskets, lift pumps, CP4 or CP3 work, and transmission repairs can matter a lot. Receipts are better than memory. Dealer history, shop invoices, parts receipts, and fleet maintenance logs all help. Missing records do not always mean the truck is bad, but they should affect price. A seller who cannot show maintenance should not get top-dollar money.