I didn't feel like pouring my money into 45 year old technology when modern radios perform so much better and are so much easier to repair. I had sent my '82's radio in for repair about 10 years ago and the needed part was no longer available. When I was told that I realized it was pointless to even think about trying to repair these old radios. There comes a time when it's pointless to beat an already dead horse.
@ 72Blackvet - The amp for the U79 radio mounts above and to the right of radio to the bottom side of the windshield frame. If you have a assembly manual, look in the option U79 section which shows how it all fits together. Somewhere I have pictures of the amp mounted in my '72 coupe when I had the whole dash assembly out. Email me at firstname.lastname@example.org and I will send them to you.
It's a pretty easy conversion, if you have all the pieces for the stereo radio. The mounting holes are already punch in the windshield frame from the factory. so no guessing exactly where the amp mounts.
@ 2Broke - ragging on about 45 year old technology isn't helpful & doesn't answer the OP original question.