I have a manual 1990 f250 Xlt lariat with a 5.8 liter engine and was wondering if I can engine swap it with the 1990 7.3 diesel engine?

 

The diesel engine will not up to the small block transmission bellhousing. It's a big swap that involves more than just the engine.

Search results using keywords "diesel engine swap" in this forum: https://www.ford-trucks.com/forums/s...rchid=35568023

 

Would I only have to switch the tranny and the engine?

 

Fuel system, additional battery cables/mount, most of the engine compartment and dash wiring, exhaust, the list continues.

What is the goal of this proposed project?

 

My main goal of the project would be a towing/off-road pick up.
Is that unrealistic?

 

Yes.

Sell, trade, horse trade your current running, factory original, reliable, serviceable truck for the truck you want. Which will be a factory original, reliable, serviceable running truck.

 

Unless you have a complete donor diesel engine truck of a similar year range, your swap is going to be very expensive and time consuming. Even with a complete donor the time involved is a lot more than you may expect. In the end you wind up with a frankentruck that tends to be very hard to sell. If the current 5.8L engine is in good shape mechanically it is a decent engine to use for towing.