I have a 1987 Subaru gl 4 wheel drive 2 barrel that's loosing coolant but nothing is coming out the exhaust , nothing in the oil and the plugs all look good any ideas were to look next

look for a puddle on top of the block, and coolant runnig off the back of the passenger side of the engine. this would be the little rubber hose under the intake to the top of the block.

 

Maybe there is a leak in the radiator or somewhere high, that it quits dripping once it gets lower than the leak.

 

Maybe the coolant is being pushed out into the overflow. Make sure to fill by the radiator cap. See if a new cap stops the coolant loss as a first attempt.