Bumping this one up for you Dave. From what I have read on other forums the cast iron unit is around 1-1/2 in. shorter. Any one out there have the measurments for a cast glide for Dave to verify ?
When I swapped the 261 with cast iron PG for the 283 Alum PG in my 62 Parisienne, I had to use the 283 drive shaft (from a 64 Parisienne). I just can't remember if it was longer or shorter.
Cast glide is shorter (1 1/2"-2"), and has course spline yoke. You need to find a later front shaft or shorten and change the yoke on the 1 you have, that's what I did on the 59.
I have a cast iron outside now in the driveway, I will measure it for u, this cast iron is from a 61 pontiac 6 cylinder. I just swapped a 305 and aluminum power glide in the 61, ahd to change the yoke because the cast iron spline had 16 and the newer powerglide had 27. The cast iron is 24 inches long