I believe the thread your looking for is 10x1.25mm
If you do not have your car turned on the vehicle will not shift out of park. You also have to have your foot of your brake.
http://www.redlinegoods.com/Elantra0105install.php
its 12x1.25
12 x 1.5
check the transaxle range switch and positioning....the holes should line up in neutral
You can find a shift solenoid diagram and pulse generator for your 1999 Hyundai and most Hyundai dealerships. Many auto-parts stores will also have the diagram.
16 x 1.5 mm thread
soory the shift solenoid
Pry out the gear selector trim with a screwdriver and lift it out.Open the console lid and remove the screws on the bottom.Remove the screws on both sides of the console.Lift the console up and over the shift lever.Disconnect any electrical connections and remove the console from vehicle.
Lots of things could be wrong. Take it to a Transmission shop and find out. Stop asking questions and just do it. Example: 2000 Hyundai Elantra shifted fine till it got up to operating temp, then would not shift out of 3rd. Problem was some bearings. Early catch can't say what it would have cost to repair. Stage the car given to mother inlaw $2300.00, New Trans from dealer would have been over $3000.00
Your shift linkage maybe going out... ~DJM
It is located on the gear shift handle.