I have a May 1970 built SS Chevelle from the Flint plant and want to close a couple of holes that were drilled in the firewall by the original owner. According to the assembly manual I have which shows running changes, the tach hole sould be on the angled part of the firewall between the wiper motor and the brake booster at this point in time. The start of production location was under the wiper motor. Does anyone have a picture of the location on a car built at this plant around this time so I make sure I close up the right hole. There are 2 holes drilled by the wiper motor and 2 in the area between the wiper motor and brake booster. I believe he used them for a mechanical tach and oil pressure guage.