My Truck is a 1999 250LD 4X4 with a 5.8
Transmissions take 3 different fluids, depending on which one.
There is no way to look at the sticker on it. The heat shield is right up against it. The pan says "Metric" and "gasket is reusable". It has 73 stamped at the forward edge of trans. The bottom edge of the build tag under TR says "E" I take this is transmission code? I want to change to filter and fluid. I just need to figure out which one is in the truck!

 

All Ford automatics including your 4R100 now use Mercon V regardless of what they originally required.

 

Thanks! I am still stuck back in the late 80's. My last truck was an 89 with a C-6.
I read somewhere to NEVER mix Mercon V with a certain trans fluid. I like that the pan has a drain plug. Less chance to make a mess.