Info on one version he
http://www.cpmt.com/tool_over_bm.php

Click on the pdf specs on the right side--has some good drawings.

I've also seen one that used a power head kind of like a handheld electric
pipe
threader. We had a guy come out and line bore the front axle pivots on a
large
4x4 John Deere tractor. Took him a couple of hours, cost around $150.