what should i charge to replace a transmission

I don't run a repair shop my shop uses repair pal to determine what they charge and as you know they don't have nearly anything that happens on a daily basis on here

Diesel is rare in a van, probably why it's not listed. If it's a 4L80E it's no different than it would be on a gas model. I'd expect it to take the same time. The only thing different is the exhaust, but I doubt that interferes on a truck.