89021672 should still be a good number. I'm sure we have it on the shelf at work.
I have always used good old 80W90 gear oil in Muncies and been 100% happy with it, although I don't drive them in the winter of course. Thinking back to the old days, I recall guys hating it in their Muncies when it was -20 outside!
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars
I have a BW super t-10 in my car and I run Lucas 80w90. I've read that you shouldn't run synthetic because it can affect the synchronizer rings. Dino oil seems to work just fine in my car.
I had the wrong number for you. It's not 89021672, that is the 80W90 but it's for posi's. 89021670 is the regular 80W90 if anyone is trying to buy it from GM.
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars
I never looked at that in the catalogue at work, I just checked that it was 80W90.
I'd still use it in a Muncie though, at least I know we did years back. It was a different part number on the bottle at that point but I think it was still the same stuff.
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars
