Buy or rent an actual pitman arm puller, do not use a tie rod fork. The following it for F150/F250 steering boxes.
ADVICE 1: Remove the pitman arm. Remove the snap ring. Thread the nut back on just a couple of turns. Crank the engine, and turn the steering wheel from stop to stop, until the pump pressure pops the seals and spacers out. The nut keeps the seals and spacers on the shaft, in correct order and orientation. Yes there will be a lot of fluid, so have a rags, drip pan or bucket VERY handy. A 5 gal bucket (too tall to fit under, cut it shorter) and then have it as close as possible to the bottom of the box.
Keep your old seals and spacers. Lay them out, in order, and oriented correctly, and then photograph them. You may need some of them. The kit can come with different thickness spacers, and might not be the same as the old ones. Fortunately, the spacers can be reused. The nut on pressure removal trick keep you from using a screw to remove both seals and possible save one.
Or another more DETAILED WAY, ADVICE 2 It’s done before with the box on the bench, but I it can be done on vehicle.
Remove the pitman arm from the steering box output shaft (sector shaft), then there's a snap ring that needs to be removed. Once that's out of the way there is a washer, then a seal, then another washer and another seal.
Remove the first washer exposing the first seal. Take a sharp center punch and pierce the seal, screw in a sheet metal screw and pry the seal out. You can do two screws 180 degrees apart too.
Once the first seal is out, remove the second washer and repeat the process. (you can also try just removing the snap ring, (after the pitman arm is off) turn the wheel to the left and start the engine, it will usually blow the whole thing out, both seals and spacers but you better have a huge drain tray under it, then reassemble.)
To replace the seals, apply a thin coating of grease to the inner lip of the seal and a thin coat of sealer to the outside diameter of the seal (I like No. 2 Permatex non-hardening).
Slide the seal over the shaft and take a deep socket that’s just slightly smaller than the OD of the seal and drive the seal in until it seats. Replace the washer then the next seal, washer then snap ring.
Reinstall the pitman arm, hook up the steering linkage and that's it.
If you don't have a socket that's deep enough you can use a piece of pipe or PVC tubing.
The killer on these is getting everything centered. With the exception of the sector shaft Ford basically only sold the internals as an assembly.
F150/F250 Steering box INPUT seal…piece of cake 30 minutes Try dealership OR……Autozone part # 8520 $8.99 in stock. Ford part # F3AZ-3E502-A Input Shaft Seal Kit…Undo bolt at rag joint, remove plastic cover on steering column (in cab) loosen steering column bolts (2 bolts to dash) pull up on column and disconnect rag joint from steering box. Drill small hole in dust seal on steering box & screw a screw in and remove seal remove snap ring, drill hole in seal remove with screw. Replace seal, snap ring, dust seal and reconnect steering column.
I was getting ready to put in new seals (that blew while out on the trail) and once I was closer to it, I seen the crack, that Saginaw box was now junk. Correct bolts...tight bolts...matter. Just some of the joys that PO's leave you to fix later.
