Hi, Kevin:
Thanks for the unexpected response.
I'm really looking for a 2-1/8" - 5 TPI threaded backplate 8" O.D. or larger that I can machine to match my 8" 4-jaw plain back chuck. However, a complete 3 or 4-jaw 8" or even 10" chuck with a backplate matching my spindle nose thread might be of interest also.
I'll send my email address by PM.
Thanks.
awright