If the circuit board has no copper place for the third contact, it's likely from a pre-1985 car. The board p/n should begin with a 6, not a 3.

The LH unit can be changed to a post-85 with the new circuit board. You will have to carve off two of the pointy circuit board locator pins near the lower outer bulb holder. Try a recycle yard first, they usually have busted up tail lights, but the board may be OK. Offer $5.00, after all who else is going to buy it? See how the bulb holder fits in, you'll see which pins to cut off.

Have a close look at the lenses on your LH light. There is a date stamp on all but the clear lens. Inner circle is the year, marks in the outer ring show the month. It is the date of manufacture of that part, not the model year of the car, so a late 1984 date could be OK.

Good Luck,

Bob

:>)