I lived in SoCal back in the early 70’s and Taco Bell sold a Bell Burger which was simply taco fixin’s on a bun. 69 cents each IIRC.
I remember when the burrito supreme came wrapped in foil and was twice the size.
I worked at TB for a summer in the mid 60s. Yes, we had a Bell Burger, two burritos, red and green, tacos, a tostada and a cup of frijoles. Everything on the menu was 19¢. You could fill up with four burritos and a Pepsi (no Coke!) for a buck.