I’m getting ready to replace my 1999 F-350 2 WD which I’ve owned for the past 26 years. Only reason for replacement is I’m in a setting now where I need 4 wheel drive and a LS rear end. Wanting to avoid as much headache as possible with the purchase of a used vehicle for replacement, what motors should I avoid?

I’m pretty certain I want to avoid the 6.0, 6.2, 6.4, and pre-2015 6.7 engines. Anything else prone to significant problems I should be aware of?

If I end up going with a gas F-250 or F-350, any certain gas motors to avoid?

 

nothing wrong with the early 6.7 engines if they were properly maintained.
same with the 6.0. if properly maintained it is a good engine. problem with the 6.0 is people either "tune" them for high HP when new and thenrun them till they break, then bitch about the "bad 6.0"
i have seen hundreds of 6.0 powered trucks that were never modified run well past 600,000 miles with proper maintenance.
the 6.2 is also a very good engine if maintained, but it is a gas hog. best i ever got with my 2014 F2504X4 was 15 mpg with cruse set at 55mph on a 500 mile run. my more realistic MPG was 9-10 mpg.

 

3V 5.4 if the history is unknown and the 6.4 boat anchor are about all you really have to avoid. At least the 6.0 has hope. The 6.4 has inherent design flaws that take tons of cash to fix. Then, you pray for the best.