Mercury greeted 1969 with a dizzying number of models and variations and a clear division between the Lincoln-Mercury models, with the larger Marquis taking a lot of Lincoln styling cues. The Montclair became the Monterey Custom line, while the Park Lane evolved into the Marquis, which included the Colony Park station wagon.

The low-line Monterey and Monterey Custom had a full-width loop-effect front bumper with turn signals wrapped around the fender. Headlights were open with horizontal grille bars in the center. The Marquis line featured covered headlights and a front more like the Lincoln Continental MK III. Side windows were now ventless and the convertible had a vinyl interior, while other models were cloth and vinyl.

Big seller in the Monterey line was the four-door sedan with 23,009 units. The convertible is rare with only 1,297 built. There were 9,865 two-door hardtops, 6,066 four-door hardtops and 5,844 wagons, for a total of 46,081 units. The Monterey Custom did not list a convertible but the other models were the same though only 14,748 were built in total with 7,103 four-door sedans as the top seller. Most Montereys were fitted with the 265 bhp 390 cid V-8.

Few changes were made in the Monterey lineup in 1970, apart from a minor grille redesign. Biggest seller in the Monterey line was the four-door sedan, at 29,432 units, followed by 9,359 two-door hardtops, 5,032 four-door hardtops and 5,164 station wagons. Only 581 convertibles were built. The Monterey Custom line shrank further with only two- and four-door hardtop, a four door sedan and no station wagon. Sales totaled only 7,374 units.

Grille and rear bumper changes marked the 1971 Monterey lines, plus a shift to on-frame construction. The grille was now many small horizontal bars that came to a point in the center, while the rear bumper was now a heavy loop design. Once again the four-door sedan was the top selling Monterey with 22,744 units, followed by 9,099 two-door hardtops, 2,482 four-door hardtops and 4,160 wagons, for a total of 38,485 units. The convertible was discontinued. Monterey Custom sales rose to 18,316 units, with 12,411 four-door sedans. Base Monterey engine was a 240 bhp 351 cid V-8, while the Custom had a 265 bhp 400 cid engine.

Montereys gained front disc brakes for 1972 and a waffle grille replaced the thin bars. Only trim levels and fancier interior distinguished the Custom line. Monterey sales slipped, with 19,012 four-door sedans, 6,731 two-door hardtops and 1,416 four-door hardtops and 4,644 wagons for a total of 31,803 units. Custom sales totaled 24,372, with 16,879 four-door sedans.

The Monterey line had effectively been replaced by the upscale Marquis and would continue to decline, finally being discontinued in 1975.