What came out first nacho or taco doritos?

My earliest recollections from the early 70's was that there were originally 3 available flavors of Doritos: Corn (just plain tortilla chips), Taco and Nacho Cheese. It may well be that they were first introduced this way. Actually: In 1966 Frito-Lay began test-marketing a new triangular tortilla chip under the brand name Doritos (meaning, when literally translated into Spanish, "little bits of gold"). Compared to regular tortilla chips, Doritos were more flavorful and crunchier. Launched nationally in 1967, Doritos proved successful, but additional market research revealed that many consumers outside the Southwest and West considered the chip to be too bland--not spicy enough for what was perceived as a Mexican snack. Frito-Lay therefore developed taco-flavored Doritos, which were introduced nationally in 1968 and were a tremendous success. Four years later, national distribution began of nacho cheese-flavored Doritos, which were also a hit.