The firewall is the metal wall that divides the passenger compartment from the engine compartment
under the rain tray in the rear of engine compartment
A 1980 Porsche 911 SC with a 3.0L flat six motor holds about 11 quarts of oil. I would use a nice 20/50 oil. Make sure to check your oil only after your engine is up to operating temp and the engine is running. Don't check it while the engine is cold and off... Brian Minson, Editor Porsche 9 Magazine www.9magazine.com
The vacuum connection for a 1980 Corvette lock-up transmission is on the passenger side of the engine compartment. It is below the air conditioning unit.
Remove the drain plug in the oil pan
Behind the passenger side kick panel.
The vehicle serial number is located on the upper face of the right side frame. The vehicle ID plate is located at the right side hood ledge in the engine compartment.
Check your fuses first.
The fuse box is located in the front passenger footwell - behind a cover.
The diagram for fuses in a 1980 300 SD can be found in the 300 service manual. The manual can be purchased through most any auto parts, and could be available for checkout at the local library.
what about it?
Hi Tony. I hate giving this answer but in this case it's the right one. A Chiltons or Haynes manual will have detailed engine rebuilding instructions and diagrams as well as photos for your reference. They cost about $20 and will be an invaluable resource for future repairs. They are available at parts stores and your public library.