This reply assumes you have good bushings on the selector rod. It also assumes the transmission is in the correct position which is controlled by good motor mounts and a good transmission mount.
Get under the car and remove the shift rod from the selector end.
You will be able to shift the transmission by hand and feel where each position is.
With a helper moving the gear selector in the car see if the position of the selector corresponds to the position of the gear the transmission is in. This will mean that when you have the transmission in Park the gear selector is in Park and the rod will be in a position that it will slip into its position on the end of the selector linkage. It should do that for all the gears.
If the rod does not slip into the hole in each gear you will need to adjust the length of the rod. It is probably rusty and care should be taken to free things up. Most likely you will need to remove the rod from under the car to do this effectively.
Adjust the rod length until it slips into the hole it rides in when the selector corresponds to the gear you have the transmission in.
Just getting the rod back in and the E-clips in place on the front one can be a challenge. Needle nose pliers and a little luck help a great deal. Lay down a large piece of cloth on the surface under the car to catch the E-clip when you drop it. Losing the E-clip can add a lot of time to this repair (as in shopping for a new one...)
Good luck,
Randy
These images are from a 240, yours may look somewhat different. The concept is the same.

Front end of shift rod with pin and E-clip

Selector link on transmission- limited space makes inserting E-clip a challenge

End of rod that is connected to the gear selector linkage.
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