Go here:
http://www.a1chips.com/magic3/V4gap/...tructions.html for gap
Go here:
http://www.a1chips.com/magic3/V4noga...tructions.html for no gap
Look at the Bios chip (connections M,N,O,P) there is a gap on the middle of the chip obviously for the gap version and no gap for the other. Another difference is that the other Bios connections (R,V,U,T,Q) are on opposite sides. Hope this helps.