I am sure this has been asked before. Has anyone ever used a Chevelle lower rear quarter panel on an Elky. Mine is a 66' as you may of guessed. I am replacing a quarter on my car from a donor car. The quarter is in real good shape other than some thin metal on the rear quarter. I don't have the means of fabricating one. Was wondering if a Chevelle could be used at all. I know there are significant difference's around the bumper, but could it work??

From experience on my '67 Elky; I obtained the left lower rear quarter patch panel for a '67 car from a supplier with the understanding that if I could not use it I would return it, just to hold it up to see if it would work. NO WAY.
The length from the rear of the fenderwell to the back of the panel is app. 31" long on the Elky and I don't remember the length of the panel for the car but it is app. four (4) inches shorter and slopes slightly upward toward the rear unlike the Elky.
If you are doing business with one of the repro suppliers and have an account they may offer you the same deal to try on your '66.
Good Luck.