10 or 29 Spline Large Yoke for T/A with 489 3rd Member?

[BillyB]

I have a 1970 Challenger T/A and it has a 741 3rd member with Sure-grip 3.91 gears. I'm guessing this is not original (I don't have a broadcast sheet to 100% confirm).

That said, as I go about putting together a correct 489 3rd member setup, should I use a 10 or 29 spline 7290 yoke? I'll also need to locate a nice 2883782 propeller shaft I suppose.....20 years and counting.....does it ever end?

Getting darn close though 

[JS29]

 @BillyB  I would think the course spline would be the way to go  What are your plans for the 3:91's with case. I might have a use for them! 

[BillyB]

Thanks for the reply JS29. Maybe some T/A aficionado will chime in to confirm 

No solid plans for the 741 setup with 3.91s.

I have a 489 case non Sure-grip with 3.23s, another 489 case, and a clutch style Sure-grip.

I also have a 69 Super Bee that needs a Sure-grip setup, but I'm not sure if that is a 741, 742, or 489 case (need to reference the broadcast sheet I suppose). I'll have to work something out across both vehicles. The Bee had a Dana 3.54 (not original) and was missing the N96 hood when I bought it 20 years ago. I traded the Dana for a cobbled together b-body 8 3/4 (with the 489, 3.23s, non Sure-grip), an extra 489 case & clutch style Sure-grip, and a rough but usable N96 hood. Now I'm trying to make heads and tails of what I got and what I need to procure to satisfy both the T/A and Super Bee builds. 

[Skdmark]

This thread has a helpful breakdown of the different rear axles.

https://forum.e-bodies.org/engine-transmission-and-rear-end/4/rearend-code/1897/