Don
Are You saying that the plug for the progressive machine is of a different size than the Universal machine ?
I don't own a progressive, but do have the dimensions for the 68U plug: 0.747 inches wide by 1.057 inches long,
made from round stock. with a slight radius [no e-mail]@ .005'') on the bottom edge (rounded over) and the top edge left sharp.
The plug could be easily machined from 3/4 inch round stock.
Hope this helped.
Lindy