Originally Posted by f350powerstroke
If they made the 6bt emissions compliant then they could've made the 4bt as well. Although I wouldn't know how that would affect the contract with Chrysler, there's plenty of buyers who'd opt for a fuel efficient diesel in an SUV or 1/2 Ton with enough brawn to pull a small camper or small block Chevy (he he) to the track
4BT, 6BT neither were ever emissions compliant nor had to be in their day, in today's standards though they wouldn't stand a chance. Far less refined also, you may have a small niche that wouldn't mind the noise or vibration and moody cold weather starting of a 6BT or 4 BT but a small niche doesn't get the bills paid.
Besides the ISB engines are far better in every way.