Engine Tin Question
 

Can someone clarify why the driver's side piece may or may not have a hole in it, depending on the part number? The part w/ the hole apparently come w/ a cap as well...

Thanks.

Depends on year of the car. Early cars had a hole on each side for heat hose pass through. Later cars 77 on had a blower motor in the engine compartment that changed the configuration of the heat system. After that there were subtle changes.

So its for a heater hose? Thanks. My '81 has the blower motor, which is why the original part I'm trying to replace doesn't have a hole...