My friend has a 99 powerstroke and he says thay they changed some things in 99 to make a 99.5. He said a good way to tell is the badging on the side of the truck, whether it'd be on the door or on the front fender. His badging is the one that should be on the door, but it is below the F-350 emblem. Is there an RPO or a VIN number that would indicate if it where a 99 or 99.5? Thanks for your help.

Early 99 had smaller turbo,intake tubes and air box.99.5 air box in one with the battery ,bigger turbo ,and intakes .We have seen some with the newer air box that also had the smaller turbo .You could pull the pcm and see what the code is xle- is 99 ,nvk- is 99.5.NLDP

Do both models have forged rods?

yes , the rods got switched out i believe late 2000 early 2001.

Thanks NLDP!

You could pull the pcm and see what the code is xle- is 99 ,nvk- is 99.5.NLDP

Using the calibration catch code (xle_, nvk_, cnh_) is most definitely NOT a reliable way to know whether a 1999 Superduty is a '99 or a '99.5. There are not only way too many calibration codes, literally hundreds, that vary based on state initially sold to, transmission, air conditioning, etc... but over the service life of the vehicle the codes in the PCM will very likely have been updated to newer calibrations per a TSB.

So, the best way to determine if 99 or 99.5 is by the engine serial number, as stamped in the block near the oil cooler, or as printed on the label on the valve cover.

All 7.3L engines from serial number 896812 or higher are considered to have ALL of the physical updates that officially classify it as a "99.5."

The reason why I say "all" is because some of the updates were incorporated earlier, individually, such as the newer fuel pressure regulator (beginning with serial number 661496), and the high pressure oil gallery plug (beginning with serial number 751869), for examples. There were other incremental updates that can interchange, such as the revised fuel filter, and the several revisions to the air filter.

But the major 99.5 update changes, such as the tungsten carbide coated injector plunger and barrel, the lower mass poppets and the wider annular split shot groove in the injectors, the higher volume high pressure oil pump to drive the revised injectors, the larger intake covers for better flow, the revised charge air cooler crossover Y that incorporates an intake air heater and revised wastegate solenoid, as well as the newer, larger turbo that has already been pointed out in a post above, all coincided with engine serial number 896812.

The approximate truck build date (as opposed to engine build date) would be between March 12-21, 1999. But the engine serial number is the still the most reliable method. Definitely not whatever calibration code might be in the computer. I wouldn't even go by the calibration code on the door, unless you have access to OASIS.

Thanks Fordiesel! Looks like some good information! Welcome to the place!