Bosch has's some pretty detailed info about their plug numbering system. The one I found has a standard length electrode, and a .875 reach (vs .750). It fits a 2.4l Nissan from the 80/90's, but it's discontinued (PN 7925). I used that to cross search and found a compatible plug. Standard reach, but with an extended electrode.
It's a standard 14mm, flat seat, .750 reach plug. But it has an electrode that is 7mm vs 4mm. That's an extra .118 of protrusion.
I haven't picked one up yet, but I have to go out today anyways, so I'm going to try and grab a test plug and I'll post pictures/results later.
Bosch Number - 6721 / FR8HPP30X
Champion - RC12MC-4
Neverlight - 5224
NISSAN 240SX 1989 - 1990 2.4L
NISSAN AXXESS 1990 24L
NISSAN D21 PICKUP 1990 - 1994 2.4L
NISSAN PICKUP 1995 - 1997 2.4L
NISSAN STANZA 1990 - 1992 2.4L
