65 Mustang steering box

[mygt350]

Is the sector "gear/shaft" in the HCC-AW and HCC-AX (16:1) ratio boxes same as found in HCC-AT (19:1) ratio box?
Is the block containing the recirculating balls that rides on the long shaft worm gear same block as found in 16:1 and 19:1 ratio boxes?
Appears only difference between a HCC-AW/HCC-AX (16:1) ratio box and a HCC-AT (19:1) ratio box is the long worm gear that seems to have either 8 or 10 grooves with 8 groves being the quicker ratio?

Thank you!

[Helmantel]

The difference between the 16:1 and 19:1 ratio boxes is in the worm gear. It's a matched set of shaft and block as the balls recirculate through the block back to the other end of the shaft and as a consequence the pitch of shaft and block needs to be the same. I never counted the grooves but the quicker ratio must have fewer per inch. I believe 19:1 is a rounded number and that ratio is actually 19+:1, so 8 for the quick box and 10 for the slow one makes sense.

[mygt350]

So the difference is the shaft AND the block?

[Helmantel]

Late answer, but yes: it's a matched set. It's basically a fancy version of a bolt (shaft) and a nut (block) and just as the thread pitch of a bolt and a nut must match, so do these steering parts.