Quarter Extension Prop Hole

Does your 1970 car have the trunk prop rod hole in the inside face of the right quarter panel extension? No? Maybe your quarter extension was replaced due to accident damage. Maybe your car is 100% original and it came from the factory without the hole? Could be either case.
Shown below is the intended location for the prop rod hole in the right quarter panel extension for the 1970 BOSS 302 Mustang.



There are two key points to this drawing. First is the note, ".250 DIA HOLE AT ASSY FOR ATTACHING L/C PROP FOR R.P.O. SPOILER R.H. O...". There is more after that last "O" but it was cut off when this was copied. Translated to plain English this note means, "1/4 inch diameter hole drilled at assembly for attaching the luggage compartment prop for regular production option spoiler right hand only." Yes, this is another one of those (if you read the radiator support hole page) items drilled by an assembly worker whenever one of these special (BOSS) cars came down the line. Which means you can't always trust the humans to do it right 100% of the time. One might hope/assume there was a special template used on the line to locate and drill this hole. I do not know if it is true or not. If you know, please tell us. We have not taken the time to compare a number of cars to see if all the holes are located approximately the same or if they vary greatly. (Should have thought of that at Carlisle, 2005).

The second key point to this drawing is the vertical dimension ".40" and the horizontal dimension "3.50" locating the center of the hole. Back when Ford used paper and pencil to design the car body, the body drawing was overlaid by equally spaced vertical and horizontal "imaginary" gridlines used for reference. The hole center here is 0.40 inches measured vertically from the gridline with the "2" in the circle off to the right of the page and 3.50 inches from something, probably a vertical gridline, running off the page to the left.
Your car doesn't have gridlines on it so you do not have a way to measure the hole location like Ford drew it. If you need to drill this hole, I can suggest a few ways to go about this.
a) Best idea: Make a template from another car. You can use this drawing to compare how well that car matches up with Ford's design intent. You can try to use paper but thin, stiff, clear plastic is best for a template. You can see through the plastic and draw on it. Plastic cuts pretty easy, too. Plastic will not bend as easy as paper unless you use heavy paper.
b) Might work idea: Use this drawing to make a template. I measured the 0.40 dimension on my copy. It measured just a smidgen over 0.40, like 0.41. That means this copy I scanned should be almost exactly full scale. About as clsoe as you can get. Print and take it to a copy machine if necessary and play with the copy size adjustments until you can measure that 0.40 EXACTLY on your copy. Then you should have your own paper template. Cut/trim it along Line V (Body Opening) and check it against the outer surface of the quarter extension. If it lines up EXACTLY (or at least to your satisfaction) then you should be good to go. Transfer it to clear plastic if you prefer.
c) Not recommended idea: Just eyeball it and drill away! Definitely not the best way to make this hole but, hey, there's "perfect" and then there's "good enough". You might settle for good enough. At least you have an idea where it should go. Did the Ford line workers have a template? Did they use it all the time? Did you check out some other cars to see if all the holes were the same? If you do, let us know the results of your survey. If you want perfection, make a template or pay someone else to do the job. Then you can blame them and have them pay for a new quarter extension and paint after they ruin yours.
One final note, there was no bushing or grommet put in the hole after it was drilled. A lot of cars may have their holes worn open and are now oversized from use through all the years.