Dang! I bet we did scare the kid off! I didn't mean to start a Cummings/Duramax war with my post
But I will say my 2003 LB7/Allison is a dream. 185K and all I've done to the truck is rebuild the instrument panel and replace the injectors at 180K. I've owned the truck from the day it rolled off the transporter.
If I was to build a diesel conversion it would be a Duramax or dare I say it??? a 7.3 Powerjoke. Say what you will, but after 12 years of production, the Duramax has proven to be a stellar platform with incredible power potential.
The Cummings is a great motor and worthy of any and all accolades it has received, but for my money a 6 banger will never be for me.
Yes, I know someone could take a 4cyl. and cram twin hair dryers/propane/NoX on it and make a 700+hp oil burner, but that's not a streetable engine.
The OP was a farm kid wanting something to pull a stock trailer, not a sled-weight or run in the low 10's. I knew a guy back in the '80 that put a cummings-perkins 4cyl. in an early '70s F**D. He was an old farmer and it suited his purpose. The truck would not outrun its own shadow, but it pulled his 2 horse trailer just fine (for him).
The OP was a kid, and knowing kids he would not be happy with a truck like that. The GM 6.2/6.5, Cummings, Duramax or PS would serve him better. He was even wanting to "Roll Coal" further leading me to believe a 4 cyl was not for him.