I think it was 1973 that they changed over to a larger shaft on the bottom end.
cwestra, I tried to measure at the top but the gap is just a whisker too tight to get my calipers in between the coupling and the box. I am wondering now why you think you have a quick ratio box ? Did they actually do a quick worm gear for the power boxes, or was it maybe just a longer pitman arm ?
Either way I would be surprised if the top seal is different on any of them. If it was you'd expect to see different sized column couplings as well, unless there was like a step in it.
Thanks for trying UKcuda. That would be great if at least the seals were the same on all boxes (regular and fast ratio). Aside from the pitman arm saying "fast ratio" on it, the box itself has "TA" stamped in the casting, which I am assuming is referencing Trans Am Racing like the motor. Also, back on Jan 19th, nqkjw commented that the shafts are different diameter (see quote below). I just don't want to buy a kit and find that it is not going to work. Hopefully someone on this site will be able to confirm it for me.
nqkjw's quote on Jan 19th:
"Quick ratio PS box kit is different.
The shafts are a smaller diameter.
Went through this hassle when I did mine and you can only imagine the problems trying to figure out in Australia what was different since the same kit is supposed to fit all from 1957 through to 1974.
This is how I found out mine was a quick ratio box.
How it ended up in mine is anyone's guess "