Q: What transmission can be swapped into my 1999 Ford Mustang?

Just because the transmissions in mustangs and crown victorias are of the same family of transmissions does not mean they are the same. You may have different gear ratios inside the transmission and also have different output shaft lengths. Your best bet is to stick to a mustang transmission of the same year or you will find the electrical connections are different . They may change between years that would take some wire diagram checks for the different years. For the price of a used transmission you could take out yours and have it rebuilt just as cheap most likely.

Your Mustang has the 4R70W automatic transmission. The application list for this transmission includes 1995-2004 Crown Victoria, so it’s possible a transmission from a ’99 Crown Vic might work. However, the part number for the transmission used in the Mustang and the part number for the Crown Victoria are different. This indicates there are probably some minor differences between the transmissions. To be safe, I recommend installing a transmission specifically designed for your Mustang. Also, the transmission from the ’92 Grand Marquis will not fit. If I’m not mistaken, that vehicle uses the AOD transmission, which is hydraulically controlled. That will not work in place of a modern, computer controlled transmission. I recommend having a professional diagnose and repair the transmission in your Mustang. YourMechanic is an excellent option since we come to your home or office.