I'd make sure the bracket connecting the transmission and shifter isn't loose first. My 2000 is notorious for this.
install transmission shifter assembly
The shifter cable connects the shifter to the transmission.
This should be really simple, if you've already removed all of the bolts which hold the shifter in including the one behind the shifter hole in the trans, the shifter should slide right down into the transmission (provided the transmission was in neutral when you pulled the shifter)
Gear shifter or manual transmission.
Remove the shifter cable and switch from the drivers side of the transmission and the seal will be driven over the small shaft and into the transmission case. The shaft is the one that the shifter cable hooked to.
You don't , you replace the linkage cable from shifter to transmission
It sounds like the transmission shifter linkage is disconnected.
For an automatic transmission, check the side of the transmission by or at where the shifter linkage goes into the trans. For a manual transmission, check under the shifter boot.
You connect your floor shifter to your transfer case in a 4x4 Chevy truck 1993 by getting under the truck and looking for the rod that comes from the shifter to the transfer case. Then, use the pin connector to connect the rod.
Those switches are all located where the shifter attaches to the top of the transmission, on the shifter iself.