I have a 65 fastback that doesn't have a depression in the right rear inner wheel well. The depression is typically there so that the spare tire will fit in the trunk. My car is a San Jose A-code car built in February. Any idea why the depression would not be present? The wheel well doesn't look like it has ever been replaced.

 

Upon reading this post I was certain my '66 coupe (that I have had for 41 years) had the spare tire indent. I went and opened the trunk lid...and it doesn't. Looking at eBay and FB Marketplace Mustangs for sale, about half of the cars with pictures of the trunk do/don't. I don't know the answer to your question (which is usually the reason for me not to respond), but I think it likely your car didn't have the depression from the factory.

 

I appreciate you taking the time to reply. I have spoken with at least one other person regarding the depression. He has at least 2 fastbacks and at least four coupes. He said all his have it and he had no idea why mine didn't. I agree with you mine is original without. A mystery I would like to solve. If I do, I will post my findings.