The South Bend (dinged) Quill Comparison

[SLK001]

A minor stumble is to get the right measurements. Are there such things as dimensioned drawings of South Bend lathe bits? I am measuring "differences" between the 9C and 9A quills. Maybe the 9C is a re-make already!
I won't bore you with the detail - just wondering if the slot is supposed to be 11/64" wide (9C) or 3/16" wide (9A).

Your best bet will be to do all the dimensioning yourself from the part you want to replace. Things changed over the years at SB. IIRC, the thread for the screw is 7/16"-10 ACME LH, but it's been a while since I had a 9". Again, check yours to be sure. A tap of that flavor can be had for less than $40 (but that is "here" and not "over there"). A 1/2" - 10 ACME LH would be easier to get for you - AliExpress has them and will ship to UK. You should use a tap to put the thread in if you're not confident in your bit grinding or threading cutting capabilities, but don't force it to do all the work. Pre-cut the thread with a single point cutter to about 85%, then finish with the tap. The pre-cut thread can be pretty sloppy, which will get cleaned up with a pass of the tap.

As for the slot, measure your key and add 0.003-0.005" for the slot - remember, things changed over the years at SB.