Will the superchips for a 99 f-350 (1704 in think) work on a 99 f-550

both have a 7.3L

 

That depends on when the 1705 was made - older units can be used only up thru the 1-ton (F-250), while the newer units can also be used on the 450's & 550's with the 7.3.

The hot tip is to call Superchips at the number ;listed in the documentation and give them the serial number from your tuner, and they can answer that for you for that particular unit.

Good luck!