In the early days of the color TV "boom" (1961-66), the only companies which were making color sets were RCA and Zenith. Everyone but Zenith used an RCA type chassis; usually a version of the CTC11, CTC12, CTC15, or CTC16. RCA made most of the early sets; apparently their design was then licensed out to other companies. Eventually most manufacturers developed their own designs, but some brands (Silvertone, Muntz, Curtis Mathes, to name a few) used the RCA design for several years. I serviced lots of them in the old days.