HELP! with Rear Trans Seal! Please!

Well all data says the number is f28511399a
and my local CSK shop says the after;market number is bs40421 so hope this helps

Yeah the 2443 is the wrong part, but after looking at it I think the driveshaft is to long and when the truck is lowered its messing up the seal. So I'm gonna try to have it shortened and see if that fixs it. thanks for everyones help with the part numbers.

Check to see if your driveshaft is pushing against the seal causing it to fail.