How many splines on a 70 727 slip yoke and where to buy the correct one?

[oldcarnut]

I want to replace mine.  I was hoping not to have to take it off and count before ordering but depending on the vender, its 29, 30, or 29 on a 30 
I also read that some sell a later 518 one and say its for both but then it doesn't fit right because of spline shape.  Do they vary that much I need to take it off first and measure to order?  I don't have too much a problem doing it but I thought they'd be all the same for BB 727s and just call it in.

[John_Kunkel]

All 727 output shafts are 30-spline, some (most) slip yokes have one dead spline to prevent air hammering so they're referred to as 29-spline but they're the same, function wise.

Some later OD transmissions have a different spline shape so they won't work in a 727. In the pic below the 46RE is on the right, 727 on the left.

[oldcarnut]

Thanks John