Some 2018 Mustang vehicles equipped with a 5.0L engine and a manual transmission may exhibit an inability to engage third and fourth gear. This may be due to a broken 3-4 shift fork. To correct the condition, follow the Service Procedure to replace the 3rd/4th shift fork, the 1st/2nd shift fork, the countershaft 3rd gear, and the 3rd/4th gear synchronizer hub and sleeve.
