According to a trucking industry news service, Paccar is in preliminary discussions to acquire Navistar International's medium - and heavy - duty truck operations, which could end up strengthening its position as one of the world's largest truck makers. Paccar, which had $8.6 billion in sales in 1999, has not taken the more serious step of due diligence, and has not made an offer. It has been reported that officials with Chicago-based Navistar initially approached Paccar to start the talks.