well as you can see from my sig... I don't either...LOL!!! I will freely admit to not owning one myself. However, I do know they get better gas milage, put out more HP and TQ (per Liter) than gas engines and in most cases run much longer than gas engines. I honestly can't justify owning a more powerfull diesel for the jobs my trucks do... I love my little I6's and the 351w I am building right now and they do everything I need them too. But if I were building a rig for pulling 15000lbs+ I would definatly go diesel! And to speak plainly I probably should have bought a diesel 6-7 years ago before I had the 5 you see below... I would have been much happier with towing trailers and the better gas milage... The 6.9 and 7.3 diesels put down some serious torque at low rpm.

While I don't know the feesability of coverting a gas 351w to 7.3L IDI... I do know it would be the best option for towing a huge load in that 88 CC... Besides I'm sure there is someone on here that can tell you the in's and out's of the conversion. No harm in considering is there???? You should try poping over to the IDI forums and asking some questions. Maybe someone with a IDI and aftermarket turbo can tell you want HP and TQ they are getting and what MPGs... Just a thought...

PS: what the heck do you need a tow rig for???? You already have 2 460's!!!

 

the bored an stroked 520/460 is a toy for wheelin. that gas mileage is around 6 on the street (almost 600 lb ft of tq)
the DD 460, is a ext shorty bed, not long enuff to pull back hoes (maybe 70 hp over stock)
the diesel is sounding more like something i need

 

I'd go have a chat with some of these guys...
Pre-Power Stroke Diesel (7.3L IDI & 6.9L) - Ford Truck Enthusiasts Forums
I have heard middle to high teens for MPGS loaded and low 20's if unloaded with wind to back and driving nice... I definatly want one myself... I will probably end up getting a 6.9L one of these days when the 4.9 and 5.8 can't handle what I want to do... until then I will just be jealous of diesel owners... Although I have been trying to talk my dad into a diesel since he wants to get a camper... I have heard the 6.9 handles the extra power of a turbo better and that the 7.3 has some problems when turbos are added... of course that is what I have read in 1 instance and can't be taken as gospel... You might want to look into a older 5.9 cummins platform with a 5 speed granny low... I know that will irradicate the fun money for extras but it will be the best engine for the job IMHO... I have no idea what it would cost but those 5.9 I6 cummins are a force to be reconned with... Let us know what you decide!