As I understand it most stations on the east coast were RCA. Ampex dominated on the west coast. RCA won an emmy in'69 for the first tape cartridge machine:
https://worldradiohistory.com/ARCHIV...ws/RCA-153.pdf
The first ACR I ever saw was at WFBC (Greenville SC) in '72 (about) but they didn't have it running 100%.
I've heard that RCA had most of the market. The TCR was about $160K and the ACR was $225K. The TCR parts were interchangeable with earlier TR70 machines. The ACR parts were not.
I helped install the TCR at WCBD (Charleston SC) in May of '76. It was the first TCR in the market. Overnight our air "look" cleaned up and blew the other stations away.
The only ACR I ever worked with was at CNN in the early 80's. I fixed an RF warning light (AFC problem) on it on my overnight shift.
The chief called me the next day to congratulate me when I was half asleep.
All I can remember telling him was that ACR is just RCA backwards. And he chuckled.