Blueprint or schematic of back plate?

[praetor]

I would like to machine a 3", four jaw chuck (plain back from cartertools/taig) onto a Seig 7" x 12" mini-lathe but don't have the real dimensions of the hole locations and register mating depth and diameter, can anyone share blueprints or guide me to a website with an actual blueprint of [spindle] back plate plans?

[praetor]

...I just ran into this:

http://warhammer.mcc.virginia.edu/ty...e-template.gif

Thanks, guys