The 1969 Ford Mustang 4 speed shifter linkage was only made for one year. The control box was completely different from the previous 4-speed stick shifters Ford made. A big reason was that the reverse lockout feature was on the shifter body and not the handle. What was the reason for its short lifespan, the reverse retainer was a piece of spring steel that was very brittle, as was the mainspring inside the housing. The useful life of these parts was probably about 65,000 miles before failure, depending on how many times the car was put in reverse. When this happened, shifting from 3rd to 2nd gear without resistance became an adventure, sometimes resulting in backing up while moving forward.
Cars that are restored today using replacement parts rarely reach 65,000 miles or are put in reverse a lot. General linkage changing has never been a big problem, some racers might argue this point, but for daily driving the linkage worked just fine. The rods and levers are similar to previous Mustang and Torino-style cars but with different curves. The Mustang’s levers are longer, and the Torino’s levers are the same as previous models.
The 1969 Ford Galaxie 4 speed gear stick control box is basically the same, but the rods and levers are different. The front shift bars are tubular and the levers are teardrop shaped, but both have the same reverse feature and had the same issue.
All replacement parts for these shifters are readily available and are of equal or better quality than the originals. Finding them can be difficult, they are not available at dealerships or auto parts stores, but they are available online from at least two sources I know of.