Thanks for all the replies.
I did find a Vertex listed on eBay, but seems the new version doesn't have a threaded spindle. Not sure what that's about ?
https://www.ebay.com/itm/Vertex-Semi-Universal-Dividing-Head-w-Plates-Tailstock-BS-0-BH-1001-050/182805329435?hash=item2a900bf61b:g:6QQAAOSwPh5ZHadUAll things considered, think I'll hold off and see if I can come up with a solution for the Carroll dividing head I have.
I picked it up on eBay a few years back for under $150, but came missing the chuck, dead center, and drive dog. Also had only one dividing plate, but did come with tailstock.
According to the literature I found, the spindle is a #9 B&S taper and 1 3/4 - 6 TPI thread.
Since then, I've had my eye out for a chuck and plates, but no luck. Not sure how hard it is to find a #9 B&S dead center or a drive dog to fit it.
Ideally, I could find a way to make an adapter so I could use my lathe chucks. Be able to go from the lathe to the dividing head without removing the work from the chuck, but not sure how I could go from the 1 3/4 -6 thread to 1 1/2 - 8 thread.
Right now, I'm thinking my best and cheapest option would be to find a piece of cast and make a chuck back-plate I could thread to fit.