[DirtyLarry]

I agree with arveetek, the 6.2 or 6.5 would be the cheapest and easiest swap for this type project. The Cummins 3.9L 4BT has come up a few times but keep in mind that engine is hard to come by as it was used by GM specifically for Frito-Lay in the Chevrolet P30 stripped chassis for only a couple of model years. You will have a hard time coming across one of those as Frito doesn’t let loose of them very often…..and believe me, you do not want to buy anything Frito has for sale. They are not exactly the benchmark fleet in terms of maintenance. The transmission adapters for that engine are even harder to come by and very expensive if you find them as well.

Between 2001 and 2005 Frito also used a Cummins 4BE with an Allison 1000 in their Workhorse P30 vans. DHL also bought a few. There were a tad over 2000 of those Workhorse P30 stepvans with 4BE’s built so they are even harder to come by than the 4BT’s and the companies that own those trucks don’t sell them very often although they can be found in some stationary equipment as well. Most people have never laid eyes on a 4BE or knew they even existed……Here is a picture of one. They shake like hell but run nice. Cummins builds great engines.