wern101
If you look on DiMarzio's site, and compare the DC resistance, you would get a close idea. It might be the "Air Classic", a "Vintage" style PAF copy, DP190F? (Air Norton is 193)
From your photo, I see the slugs are thinner at the bottom, which does suggest the "Air" version - They thinned down the slugs at the bottom to accommodate rings to space them from the magnet.
As mentioned, "F" probably indicates "F Spaced", or "Trembucker"" in Duncan Speak, accommodating wider string spacing for Floyd style bridges.
The Air Classic should be a very nice pickup, open, clear, bright...
Have fun.