The easiest place to look would be on the back of the engine towars the trans above the passenger axle.. If it is a 1979 engine it will having nothing cast ther and woudl be a 1.5.. If it says 1.6D then it's a later 1.6 of some variety..
There is also an engine code on the front of the block, right below the head sort of between the #3 and #4 injectors.. Sort of a bear to see since it is right behind the coolant bypass hose.. These would be the most likely candidates for what you have..
CK =1.5 NA
CR = Early 1.6 NA w/ 11mm head bolts
CY & MF = 1.6 Turbo Diesel
ME = Later 1.6 NA w/ 12mm head bolts
If you have a CK or a CR engine carefully check the deck of your engine block for cracks around the head bolt holes.. They are famous for this... IF the deck checks out okay you NEED head studs for reassembly.. THey both prefent cracking, and repeated gasket failures...