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D30 One-piece shaft conversion correct seal

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I've been working on my '87 dana 30 HP vaccum diso with 4.10's to match my 8.8. when doing the one piece shaft conversion(shafts from either a TJ/XJ/ZJ) we need to add a seal inside the pumpkin on the passenger side. all my forum searching lead to seal National p/n 471763 or Napa 11800. both seals have an outer diameter of 2.004" for a a housing bore of 2". I busted mine while trying to install it bc my Housing bore is smaller. I used the National seals book at O'reilly and found the right seal If you're doing this on a early Dana 30. My '87 dana 30's housing bore is 1.975" I found:


National p/n 471747

Shaft Size=1.125"

Housing Bore=1.983

Outer Diameter=1.987



put it in the freezer for 1/2 hour and it works!!!

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I used Napa 11771 (National equivalent is 40576s) which has a bore size of 1.996" and fit perfectly in my 87 D30. A friend recently converted his (don't know offhand what year) and used that same one.

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When I swapped out the 2 piece shaft for a 1 piece I just cleaned the housing out really good and installed some Alloy Tube Seals and overfilled the diff by about a half quart and ran it like that for allmost 2 years . After that I got it regeard and the shop put in the approiate seal but I don't know the # .

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