The Cummins 5.9L "B-Series" diesel engine was produced from 1984 up until 2007. First generation versions were named the 6BT but also commonly referred to as the 12v, or 12-valve. Each cylinder had 2 valves, hence the name 12-valve. Midway through 1998, the 6BT was replaced with the ISB, which stands for "Interact System B". Here is our article on Cummins 5.9 12v engine … [Read more...] about The 4 Most Common Cummins 5.9L Engine Problems