Can this be answered without pulling the driveshaft and measuring?

The car is a 1973 Charger 400-4bbl with a 489 8 3/4 rear. The ring/pinion isn't original but the driveshaft and yoke is. The rear was originally a 2.76 open diff FWIW.

What spline and u-joint size would this be or is that a roll of the dice?

Thanks!!!

Should be a 7290...no need to pull the driveshaft to check, just measure across the yoke with calipers.

Any idea on the spline count? 10 or 29?

it originally came with a 29 spline.

Dangit. So why is that all the aftermarket 29 spline yokes seem to be in only 7960 or 1350 spicer u-joint??

The only yoke I can find that is 29 spline and 7960 u-joint is this one:
HERE

I am guessing this is more or less a stock replacement. I feel that if I am going to spend the money on a new yoke, I'd like to upgrade to a stronger one.

Any ideas if this one would stand up to occasional spirited street driving with a 499 stoker 727 auto in front of it??

Do the repair sleeves work or should I avoid them??

This is all due to a long running leak I have with my pinion seal which nobody seems to be able to fix. I am wondering if everybody is just incompetent where they can't do it right or maybe my yoke is grooved??

3432487 is a 8 3/4 29 spline yoke 7290. brads nos shows online that they have one. mopar still sells them but you won`t like the price. make sure that is what you need before you order. some b bodies with 8 3/4 came with the small joint also but a 400 4bl should be a large joint. http://www.bradsnosparts.com/inventory/searchResults.asp

I measured the outside of the yoke and subtracted 2x the thickness of the ends and come up with 2.6". This probably isn't super accurate as I did this with the car on the ground with me stretching to get the calipers over to the yoke from behind.

I am guessing the 2.6" is really 2.625 which would be 2 5/8" so 7290 u joint?

I also fiddled with the axle vent on the brake line tee and now there is a little oil that puked from there. I topped it off a few weeks ago (bottom of fill hole). Is this normal?

I see Dr. Diff has the 29 spline 7290 yoke here .

Will this be what I need? Also my current u-joint has straps...this one has u-bolts. Any issues there? I heard u-bolts are better?

Sorry to be an ignoramus but I have never put much thought into the differential/driveline since I had that re-done years ago.

Thanks!

That must be a generic pic in that listing. You can see the yoke is clearly a 10 spline. And yes the fine spline yoke you need would use straps and bolts.

Measure the hex size of the pinion nut; if it's 1 1/8" it's 10-spline, if it's 1 1/4" or larger it's 29-spline.