The FJ-4B was a ground attack version of the FJ-4, and was in fact built in larger numbers than the original FJ-4. It was similar in concept to the F-86H Sabre, although there was no direct relationship between the two aircraft other than their common ancestry.

The FJ-4B differed from the FJ-4 by being strengthened to take six underwing ordinance stations capable of carrying a total of up to 6000 pounds of fuel tanks, rockets, or bombs. It could carry up to four underwing drop tanks (2 150-gallon and/or 2 200 gallon tanks).

The FJ-4B was equipped with a set of flight spoilers situated just ahead of the trailing-edge flaps, which were used at low altitudes and high Mach numbers to improve the controllability.

The FJ-4B was also fitted with an additional pair of speed brakes underneath the fuselage near the tail. These brakes were linked to the main speed brakes on the fuselage sides just aft of the wing trailing edge and could be used to reduce speed during low-level bombing attacks. However, the primary purpose of these additional brakes was to reduce carrier landing speeds and to give the aircraft better go-around capabilities in case of a bolter. The brakes made it possible to use a higher engine RPM during landings, avoiding a regime in which the engine ran roughly. Just before landing, these additional brakes were automatically closed when the undercarriage was lowered to prevent the brakes from scraping on the deck during landings. All four of the speed brakes were activated by a single switch on the throttle lever.

Found the above info here: http://home.att.net/~jbaugher1/p86_24.html