6.2 to 6.5

I have a 98 GMC Grumman stepvan, last week the motor blew. I was lucky to find a Chevy cube truck (government surplus) very clean and low miles, Because the truck carcass was going to the junkyard we were able to pull the motor and trans fully intact. At this point I sent the truck to the mechanic to complete the swap. This morning the mechanic called me and told me, as he began to dig in, he soon realized the existing blown motor was actually a 6.2 diesel. My question: is it worth it to convert the 6.5 and use it, or am I better off finding a 6.2 which I really don't want to do. Keep in mind The 6.5 has less than 15,000 miles on it, also I am hemorrhaging money every day the truck is idle. I look forward to your suggestions. SD

Welcome aboard!

The 6.2 and 6.5 long blocks are interchangeable, especially so within chassis applications, such as yours. The actual displacement isn't relevant. If both have a serpentine belt, it should be seamless (a V-belt would indicate a much earlier model complete swap). If the belts are different, have your mechanic look at the intake manifold bolts (easiest method to determine the application). If the bolts are right angle into the heads, it's a "truck" engine. If they are vertical, it is a "van" engine, which is what yours was originally, with the only notable difference being the heads. There are some differences between the fuel systems over the years (injection pump, lines, and injectors), but you can use the one that fits if they are different. You can either do a complete swap (intake to pan), including fuel system, or just swap the long blocks.

If yours was a 98 with a 6.2 then somebody has already done the switch from 6.5 to 6.2
So going back to stock in your case should be easy.