What did the Trans Am Cudas & Challengers run for rear ends?

8.75's

Iirc, they were floater rears. So different rear bearings. Should be two for each side.

NASCAR Mopars at the time used 8.75's but ran floaters. I'd have to look in the Petty catalog, but they should be completely different and larger bearings.

The basic 8.75 setup is Daytona proven to handle ?700 hp at speed behind a Hemi + MT. A hard standing start like HSAX with really sticky track tires and steeper gears is a different situation that could hurt it... as on a drag car.

when i first inquired about the axle bearings that were in the dana for my humpback panel truck, i thought they had already been trashed because they were not a sealed bearing [open on the inboard side]. these came installed on the axles from strange, and the rear had never been run as it was a new , narrowed unit. the ends were the "big ford" bearing ends, i believe the od. is 3.150". anyway, i supplied the good doc with the part # on the bearings and several pics, and he told me those were for a 57 olds and they were the best a guy could get because they were open on the back side for using diff lube. however, they are not made any more or are very hard to obtain, i forget which. he told me at the time, which was at least 10 years or so ago. so, . i'll go with what he says and not worry about it. but my use is far from a serious cornering application.

I'm seriously considering an Aluminum D-44 from a 98 Grand Cherokee. The Aluminum center section uses the same HD ring and Pinion that the Viper uses, and they seem to hold up well behind turbo'd and Supercharged V-10s. If it doesn't work I'll only be out the 100$ that Pull a part gets for the axle and my labor.

I would think the D44, like the 8.75, would hold up fine in a cornering application until you combine lots of HP, really sticky tires, a manual transmission and hard launches.

I don't know about fit, and impact on the driveshaft and angles... but you could get disk brakes for low cost that way. Otherwise, I would (and did) stick with the 8.75. It serves me well with ~590 HP and ~680 ft lb torque and manual transmission... with 200 TW tires. I'm just concerned If I switch to 50 TW tires, it will let go on hard launch.

My understanding, the D44's used in Vipers were heavily beefed with special alloy parts and much stronger than the SUV version. With 50 TW track tires or slicks, I would guess a hard launch would break a Viper D44 also. That's probably why Viper drag racers switch to a D60.

You could just go with a Mag Dana 60.

FWIW, a rather rare MW Alum 8.75, shown first with 3.55 R&P and billet yoke, changed out to a lighter 2.76 and alum small Mopar yoke. Its a Auburn, not sure why 20? years ago i went that route. Notice the thickness of the mounting flange, caused a few issues installing. The weight on the scale is shown.

What's the weight of a regular castiron 3rd member? I'm guessing around 90 lbs somewhere?

The aluminum D44 from the ZJ Grand Cherokee uses the same internals as the Viper D-44. The only time Viper guys ever seem to go away from the D-44 is when they ditch the IFS. There are 1200 HP Vipers using the stock D-44 rear axle. As for fitment it has the same 5 on 4.5" pattern and is 59.5" wide WMS to WMS so it is a perfect fit for my 70 Bird clone

My 742 with power lock sure grip weighed 75lbs. I am guessing that the cone type grips are a couple pounds heavier than clutch, though no positive.

The AL 3rd members don't save much.

Why the threaded flange behind the yoke on the AL unit????

Not sure, my guess its either for a circle track J bar mount, or a flange for mounting a DS powered alternator or pump. The one pictured came out of a dragster.

Thought the Vipers ended up with a "Super 44"?

They did, and the Grand Cherokees did too.

The aluminum dana 44 flexes too much, lots of them were junked in grocery getters