Rear End Pinion/Yoke Size??

[Glow Worm]

Is it possible to determine - without disassembly -  what size yoke I have?  I don't know if it is big or small, or if it is 10 spline or 29 spline.

I've seen numbers thrown around like 7290,  7260,  72640,  1350, etc., etc.  Do the yokes have numbers on them?

The car is a 1973 'Cuda 340.  The case is a 489.  Sure grip.

I'm trying to get some advance info without getting under the car (yet) so I can get it repaired (again).  I provided a new ring and pinion and new bearing kit to the "mechanic" almost 2 years ago so everything inside should be new.   He said the pinion wouldn't fit my yoke so he replaced it with the correct one. Just wasn't properly set up when it was put back together. 

[Burdar]

I believe a 73 would of had a 29 spline originally. Since the gears were replaced, it could have either.

The pinion nut is a different size between a 10 and 29 spline. Measuring the nut will tell you what you have.

[RUNCHARGER]

You can measure crossways across the yoke as well. I am going off memory but I think a 7290 yoke measures 3 3/4" across and a 7260 yoke measures 3 3/8" across.

[Chryco Psycho]

Measuring Inside the ears on the yolk The 7260 (2-1/8" yoke ID) and the 7290 (2-5/8" yoke ID)

[Morty426]

So we are afraid you need to get under the car   

[ply64post]

    Inside snap rings used by the '7260' and '7290'. The cap diameter for the '7260' is 1.078" and cap diameter for the '7290' is 1.126". 7260 inside measurement is 2 1/8" and the 7290 is 2 5/8"s.The 741 - 742' assemblies used a coarse spline (10 splines) drive pinion. In period of 69-71 for the '489' unit, there were several spline  pinion size and yoke availability. 69-70 '489' units may be equipped with a coarse (10) spline pinion, particularly for the '7290'. There are two yokes for the '7260' and '7290' universal joints with fine (29) splines.     
How Many Splines? '489 Case, 8 3/4 Rear, 2 1/8" Yoke

So, how Many Splines, 10 or 29? '489 Case, 8 3/4 Rear, 2 1/8" Yoke.

If the pinion nut takes a 1 1/8 socket, it is a 10 spline. If the pinion nut takes a 1 1/4 or 1 5/16 socket, it is a 29 spline.