Flygga From , joined Dec 1969, posts, RR:
Reply 2, posted (14 years 1 month 6 days 11 hours ago) and read 1108 times:
They are "vortex dissipaters". They are part of the gravel runway kit that was an option on the B737-200 for operations at unimproved airports. They are used to help prevent debris from being ingested into the engines. Another part of the gravel kit visible on this plane is the gravel deflectors of the side of the fuselage near the nose wheel.