From a post on another thread regarding the KW and Peterbilt color for engines: Peterbilt had mostly white engines up to 1984...even the Detroit Diesel's...that's quite funny tho' as the Detroit Diesels are known to leak oil almost everywhere. Both Peterbilt and Kenworth had white engines, Kenworth had them until 1975 and Peterbilt until 1984 as I said...but I have seen white engines on pictures of trucks newer than that and engine factory colors on trucks older than that, so there are exceptions to the rule.Caterpillar was appearently the last manufacturer to deliver white engines to Peterbilt.