Just ran across an eBag auction that appears to be advertising (from a reputable source BTW) a single 8.75 pinion seal that works on both the 489 and 741 cases. I was under the impression that they all used different seals. I double-checked the tech archives and sure enough they list different National part numbers. Further research here and here show them as having different dimensions also.

Can anyone shed some light as I am currently in need of a 741 seal and have a 489 one on hand but don't want to open the pig until I'm certain that I have the parts to complete the job correctly.

Thanks in advance!

The part number in the tech archives is year specific. 741 and 489 castings use the same pinion seal. The 742 case uses a different one, however.

Cool - I got the master of Mopar rearends

It really is nice BTW to have you mega-experienced guys chime in w/the definitive answers - it is obvious that despite the online harassment, you guys continue to share...kudos!

OK enough lip-service, maybe you can clarify the year-specific part and maybe help me (and hopefully others) understand the info in the archives - which says:

--begin archive snip--

By the way, these are National seal numbers, and BCA bearing numbers. Dennis

8 3/4" 3rd member bearings.

741 case
Differential 57-early 69: 25590/25520
Differential Late 69-74: LM104949/LM104912
Pinion inner: HM89446/HM89410
Pinion outer:M88048/M88010
Seal: 8515N

742 case
Differential : 25590/25520
Pinion inner: HM803149/HM803110
Pinion outer: HM89443/HM89410
Seal: 7216

489 case
Differential: LM104949/LM104912
Pinion inner: M804049/M804010
Pinion outer: M88048/M88010
Seal: 5126

--end archive snip--

I'm assuming that the line starting with "Seal:" is the pinion seal since it comes after the pinion bearing numbers. When I look up the dimensions of these seals - they are different as I would expect considering different part numbers.

Is there a National part number for the "works with both 741 and 489 case" pinion seal -or- is it one of the two listed in the archive (which?). Can you see the confusion?

Thanks again!