Just look down the side on the Drivers side and see if you can see a sensor or wire going to a sensor on the side of the oil pan.. with a flashlight you should be able to see it from the top no problem.
Turn the key on. If you have an oil indicator on the right hand side that is lit. You will have the sender. If it doesn't come on, either you don't have it, or the bulb or sender is defective.
Yes there are two different oil pans, with 89 (i think) as the change date.
The oil pump pick up tube on the pre 89`s will hit the pan made after 89.
The area in question is the part between the two humps, its slopped on the sides or not .