Speedo pinion gears

Bumping this for another try.

It's been years ago that I swapped in a different 833. I question the 'smaller mainshaft' idea. Maybe it was a -60/-90 U-joint difference. I do recall I needed a different slip yoke from what the '69 833 had in it.

Also, what is the application differences for a short or long speedo pinion? Is there a year they changed in A bodies?

Anyway, I'm still looking for a 2538945 (according to moparts.org) yellow speedo pinion. Short or long is a question.

Thanks.