Will a 84 crown vic tranny fit in a grand marq 89?

Yes, a transmission from an 1984 Crown Victoria can fit into a 1989 Grand Marquis, as both vehicles share similar platform designs and components due to being part of Ford's Panther platform. However, it's important to verify compatibility regarding specific connections, mounts, and any electronic controls that may differ between the two model years. Always consult a service manual or a professional to ensure a proper fit and function.