The 1969 Ford Mustang 4 speed shifter linkage was only made for one year. The control box was completely different from the 4-speed paddle shifters that Ford made. One big reason was that the reverse lock feature was on the gear lever body and not the handle. Which was the reason for its short life, the reverse seal was a piece of spring steel that was very brittle just like the mainspring inside the housing. The 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, which at some point resulted in going into reverse while moving forward.
Cars that are restored today using replacement parts will rarely hit 65,000 miles or reverse a lot. Overall linkage change has never been a big deal, some speed racers may argue this point, but for everyday riding the linkage worked well. The rods and levers are similar to those on previous Mustang and Torino cars, but with different curves. The Mustang levers are longer and the Torino levers are the same as on previous models.
The 1969 4 speed gear stick control box for the Ford Galaxie is basically the same, but the rods and levers are different. The forward gear rods are tubular and the levers are teardrop shaped, but they both have the same reverse gear feature and have the same problem.
All replacement parts for these shifters are available and are of equal or better quality than the originals. Finding them can be difficult, they are not available from dealers or auto parts stores, but they are available online from at least two sources that I know of.