I've been looking at a 2005 Chevy Silverado 2500 equipped with the duramax diesel at a local GM dealer near me. The truck has 236 000 km or about 150 000 miles. Wasn't used for anything but personal transportation. Asking price is $18 000 Canadian. I was wondering a few things about this truck: 1. How long does a duramax diesel and allison tranny last? 2. Any known issues with this year of truck? 3. Fuel economy? Thanks.