I think the BF-82 equates to a 46 nowadays. Just short of a glowplug.

http://ford-y-block.com 

20 miles east of San Diego, 20 miles north of Mexico

Paul:

Those are later versions of the old BF82. They are good for a stock Y in city use, even for short highway trips. May be a little hot for extended highway travel or police work.

John - "The Hoosier Hurricane"

I have on hand Motorcraft 18mm - BSF82C spark plugs, which I assume are old stock, as they apparently don't appear on a current Motorcraft list. I had no luck trying to cross reference them to Champion or Autolite. Anyone familiar with them & know if they are suitable for a stock Y-Block for mainly city use? Thanks

Paul