now that the nut and yoke flange are off, I can't get the pinion seal and metal casting loose. what type of tool should I use???

I've been trying at it with a pair of pliers, a flat head screw driver and a hammer...all to no avail.

Is the lip that appears on the outside of the differential case attached to the oil seal? or is it similar to the aftermarket seal in that it has NO lip? I've heard that some seals have the lip.

what is the best method for loosening the oil seal casting?? a punch and hammer, pry it out???? I'm stuck and so is the oil seal. all help is once again much appreciated!

Go ahead and have your way with it. You may be able to cut it with a Ford tool & a sharp chisel. Maybe go in thru the case w/ a long drift or screwdriver that you don't mind hitting w/ a Ford tool.But MAKE SURE you are on the seal, not the inside seat of the case.
Good luck.

i finally got it out. i took a closer look at the seal casting and realized that the seal casting on the original pinion seal does have a lip on it. i just proceeded to drive a screw driver under the lip and eventually it popped out. I just hope that the aftermarket seal that I have is correct, as it doesn't have the lip. it is the correct diameter though. we'll see.

I would take whats left of the old seal, and the replacement one back to where u got it and try to match it up to a new one w/ the lip. If this is not an option, then make sure that the sealing surface of the new 1 pretty much seals your pinion shaft just about the same place the old seal did. Inthat case,I would get a tool for driving it into place,(large socket, peice of pipe w/ same diameter, or an actual seal install tool). Although I've personally never seen one. Then make sure u'r driving the seal in place squarely, only tappin it part way in, then drop the OLD PINION W/ SHIMS IN THE CASE AND USE THAT FOR A GUAGE TO SET THE SEAL. EVEN IF U'R REPLACING THE PINION, THAS WILL GIVE U THE PROPER PLACE FOR THE SEAL TO RIDE.
Good luck.