Will a transmission from 1999 explorer fit 1997 ford f150?

No, a transmission from a 1999 Ford Explorer will almost certainly not fit a 1997 Ford F-150. While both are Ford vehicles, they use different transmissions and drivetrain configurations. The F-150 is a much heavier truck and requires a much more robust transmission. Even if the bolt patterns *might* coincidentally match (highly unlikely), the internal components, gear ratios, and overall strength would be vastly different and incompatible. Attempting to install it would be a significant waste of time and effort, and likely cause damage.