There is a box about 8" x 2" x 6" under the drivers seat on my '83. Could this be the old computer?
Chuck

 

Sure. Post pics.

 

This is what I found...

 

Yes, that looks like an EEC. Can you get a shot of any labels on it? The nuts on the sides holding it down to the floor are probably 7/16" (11mm).

 

Can you take a few more photos?

 

I will take some more pics. Got side tracked today working on windshield wiper linkage. Passenger side wiper was inop. Had to pull the wiper motor to get the linkage out. Replaced the linkage bushings, no problem until I tried to re-install the wiper motor. Super fustrating. Had to suspend the struggle and have a beer or 3. Hope it goes better tomorrow.
I look like a poster child for a band-aid commercial... I have cuts on my hands, forearms, elbows, and my back is aching! Next project vehicle is going to be a lot smaller! Maybe a Mini...
Chuck

 

Smaller vehicles are NOT easier to work on.

 

It was indeed the EEC. I removed it, patched the floor, and removed the harness and associated vacuum switches. I forgot to take pictures but I still have the EEC and the associated wiring and junk I removed. I can take pics if needed.