The item being offered is the old part # 321782R93 Seal that was used on the 180 Payhaulers which was updated to part number 1141223C1 which was then used in production of the 350 & 350B/C trucks.   This is a totally different type of seal as you can see by the pictures.  The 321782R93 is a "lip"  type seal where as the newer style (1141223C1) is more of a square rubber seal that turns within itself. The 1141223C1 Seal is now obsolete and nearly impossible to find.   As of right now, I don't believe they will ever be making them again.  In the photos, the one you are bidding on is the "old style" silver and black seal. I also posted a photo of the red 1141223C1 "newer style"  seal (National # 396412VXO) just so you could see the difference when comparing the two.  If you have any questions, please call (630) 833-7400 and I will try to answer them for you.  Thanks for looking.