The gear shifter in my son's '93 Bronco (automatic transmission) is stuck in drive. Any ideas?

Does the shift lever move and the transmission not change gear or is the lever stuck. If the lever moves but nothing changes your shift linkage has come disconnected somewhere between the transmission and the shifter. This is an older truck so the linkage may have also rusted apart. If the shifter will not move check your brake shift interlock fuse.

It's probably the transmission control shift cable they come apart and slide over the top of it's self. Where the thicker rubber sleeve. Ford over the small plastic sleeve