If it has the serial number tag with 6 digit number, take the first and fourth numbe and put them together and subtract 3 to determine the year.
The L engine is basically the same as the later LA engine and these parts can be used in the L engine. Early L water pumps are different if they have flat belt, but V-belt puley pumps are the same. They have a grease seal pessure seal, so if they leak try adding grease to the cup and turn down till you feel pressure on the cup.
Transmissions and final drives are bull strong and seldom cause problems. May want to check the final drive chains for excessive stretch.