<VV> Need some advice on LM Yoke Breakage

[BBRT]

 Folks, I need your advice on why the driver's side yoke on the '66 Corvair 
failed. This is a track car with reasonable horsepower and "jarring" clutch. 
The car uses an upper and lower control arm and therefore floats the axle 
without a bolt holding the yoke in. The axle is no longer the upper control 
arm.  The "U Joint Yoke (UJY) nuts" were left in the carrier, but not bolted 
down.  The yoke on the #89 was broken in the splines, outward from the inner 
end, an amount equal to the depth of the "UJY nut" that sticks in the yoke 
hole.  Recall the "UJY nut" has the inboard end which is flat with 25 
"teeth" to mate with the inner splines of the side gear. On the outboard 
side, which mates to the yoke, there is a cylindrical portion which sticks 
inside the yoke, and when the long bolt is tightened to the threaded hole in 
the "UJY nut", it draws the two together, with the "UJY nut" teeth within 
the  portion of the inner splines of the side gear.  It cannot go all the 
way in, because there is a larger diameter on the "UJY nut" which butts up 
agains the side gear. I have been told when floating the axle, ro remove the 
" UJY nuts".

Why do you think the yoke failed there?  BTW, I have all of the pieces apart 
in a box and can send pictures.

Thanks in advance.

Chuck S