1999 GMC jimmy is leaking anti-freeze, not over heating. Only small leakage. What...

[ReeRee]

...could this be?
Leaking from the rear on the right side.

 

[Mark C]

The 4.3 gm engine is known for intake gasket failure.. that's where your coolant is most likely from!
good luck,mark

 

[ptcruisher2001]

cracked radiator, a hose is leaking, bad gasket one or all of the above

 

[fwf43]

Where is the area of the leak, front or rear of the engine? The coolant could be leaking from a number of places.