1999 F350

Kept my '99 washed and the pocket areas cleaned out until the rust started anyway, then gave up, cab corners, bed wheel well lip, door lower edges all fell prey to the great horned Iron Worms.  If could find a decent 99 or 00 no rust cab for less than the cost of a full truck would consider one to extend the life of mine, but it is still a 21 year old wagon along with 340,000 miles.

The 7.3 Navistar, although not as powerful as the later 6.0 'Ford-modified' Navistar, and on Ford engines, was in our opinion the much more durable, much more reliable, and due to repairs we experienced on the laters, much LOWER cost to operate than any other Ford diesel light truck powerplant offered.

Diesels are ALL challenged by cold winter starts.  On the 7.3's , we had dual tanks, front was around 18 gallons, rear was 38ish (? senior moment)...  we would run the front tank down to less than 1/8, then [pour in one gallon of premium gasoline, and fill the tank with #2 diesel, then fill the rear with #2.  We'd run them on the rear tank until a really cold snap was expected, then we'd switch to the front tank a mile and a half from home, then shut them down... we'd run engine heater for an hour, restart on the front tank, and once warm, switch to the rear, and it worked flawlessly to '-30F.

7.3 as a "disposable' 100,000 mile engine?  I don't agree there.  When we had 7.3's, we our fleet program was buy-and-sell, meaning, we purchased them outright, fitted our service bodies, and ran them until we deemed it necessary to refresh the fleet.  We ran them about 175,000 miles over a 3 -4 year timeframe... we had 7.3's active in our fleet starting 1993 and while we started a 2-year lease program into 6.0l in 2003, we did not sell off our last 7.3L until 2007, it had 560,000mi on it.

We DID experience a few transmission issues... IIRC those were Allison 5-speed autos, but less than our 6.0 and later fleets.  We had one rear axle that had a problem, seized pinion bearing I think.  We did NO intake, exhaust, 'chip' or programming modifications in any of our trucks.  They got service body mounted, and electricals connected to power the box lights, and went to work.

The opinion of all our guys that operated our fleet at that time, and later, agree that while not as powerful as later units, the 7.3 was the most cost-effective engine of any of our fleets.

They will also note that our fuel economy for the 7.3 fleets was substantially better than any later versions... we were getting 18-19mpg on those... two engine generations later, we were lucky to get over 6mpg.