88 t-bird V8 with auto transmission and shifter mounted on the floor console, will not go into park or first gear. It has a t-handle with a button on the left side of the handle that you press when you want to go into park.

may fit but one may be computer controlled and the other not , which will create problems
talk with a auto transmission service shop to get the exact differences

What year is it ? Does yours have floor mounted gear shifter on the console ?
Ignition Lock Cylinder Control Actuator
If the vehicle is equipped with a floor mounted console gear shifter, it has a ignition lock cylinder control actuator system in the steering column. The ignition lock cylinder control actuator's purpose is to prevent the ignition key from being turned to the OFF position when the transmission is in gear and the vehicle may still be moving. The column ignition lock system consists of a ignition lock cylinder control actuator , and a Park position switch that is located in the automatic transmission (A/T) shift lock control switch. The ignition lock cylinder control actuator contains a pin that is spring loaded out to mechanically prevent the ignition key cylinder from being turned to the Lock position when vehicle transmission is not in the Park position. If vehicle power is lost, and/or the transmission is not in the Park position the operator will not be able to turn the ignition key to the Lock position and will not be able to remove the ignition key from the column.

rtm? no symptoms so i must guess, ill say , cant shift. and is not park lock out causing that.
want to read the manual or me to you.'?
ill guess you.

http://www.jeep4x4center.com/knowledge-base/index.htm?utm_source=cj#service

click 1996 to 2001
it replaces like all cables do
detach both ends and remove it. if clamps seen those too.
what matters is adjustment is needed.

some have 2 cables, one to gear box and one to ignition switch.
Chapter 21, page 150 states
REMOVAL
(1) Shift transmission into Park.
(2) Remove shift lever bezel and necessary console
parts for access to shift lever assembly.
(3) Disconnect cable at shift lever and feed cable
through dash panel opening to underside of vehicle.
(4) Raise vehicle.
(5) Disengage cable eyelet at transmission shift
lever and pull cable adjuster out of mounting
bracket. Then remove old cable from vehicle.
INSTALLATION
(1) Route cable through hole in dash panel. Fully
seat cable grommet into dash panel.
(2) Place the auto transmission manual shift control
lever in "Park" detent (rearmost) position and
rotate prop shaft to ensure transmission is in park.
(3) Connect shift cable to shifter mechanism by
snapping cable retaining ears into shifter bracket
and press cable end fitting onto lever ball stud.
(4) Place the floor shifter lever in park position.
Ensure that the pawl is seated within the confines of
the adjustment gauge clip.
(5) Snap the cable into the transmission bracket so
the retaining ears are engaged and connect cable end
fitting onto the manual control lever ball stud.
(6) Lock shift cable into position by pushing
upward on the adjusting lock button.
(7) Remove and discard the shift cable adjustment
gauge clip from the park gate of the shifter.

easy?

What make vehicle ? Most all vehicles have a safety system .Don't try an force anything you'll break it !
Electronic Park Lock (EPL)/Ignition Lock Cylinder Control Actuator: If the vehicle is equipped with automatic transmission and a floor mounted console gear shift, it has an ignition lock cylinder control actuator system in the steering column. The ignition lock cylinder control actuator purpose is to prevent the ignition key from being turned to the OFF position when the transmission is in any position other than PARK and the vehicle may still be moving. The column ignition lock system consists of an ignition lock cylinder control actuator, and a park position switch that is located in the automatic transmission shift lock control switch. The ignition lock cylinder control actuator contains a pin that is spring loaded to mechanically prevent the ignition key cylinder from being turned to the lock position when the vehicle transmission is not in the PARK position. If vehicle power is lost, and/or the transmission is not in the PARK position the operator will not be able to turn the ignition key to the lock position and will not be able to remove the ignition key from the column. They also have this on column mounted shifters !

Ignition Lock Cylinder Control Actuator
If the vehicle is equipped with a floor mounted console gear shifter, it has a ignition lock cylinder control actuator system in the steering column as an added safety feature. The ignition lock cylinder control actuators purpose is to prevent the steering wheel from being locked when the transmission is in gear and the vehicle may still be moving. The column ignition lock system consists of a ignition lock cylinder control acutator, and a park position switch that is located in the A/T shift lock control switch. The ignition lock cylinder control acutator contains a pin that is spring loaded out to mechanically prevent the ignition key cylinder from being turned to the lock position when vehicle transmission is not in the Park position. If vehicle power is lost, and/or the transmission is not in the Park position the operator will not be able to turn the ignition key to the lock position and will not be able to remove the ignition key from the column. GM has had some problems with this , If you have the console shifter there is a micro switch that when put into park a linkage pushes on this micro switch closing the circuit to ignition lock cylinder control actuator allowing you to remove your key ! These linkages fall out causing this problem ,an have electrical wiring problems as well ! I fixed a 2006 Chevy cobalt that had this same problem by getting a used shifter assembly at the auto salvage year ! cost $20.00 . There mite be a access hole under the bottom of the steering column with a release button up inside !

Does it go into the lock position ? Will the shifter go into the park position ? Is it a automatic transmission ?
Electronic Park Lock (EPL)/Ignition Lock Cylinder Control Actuator: If the vehicle is equipped with automatic transmission and a floor mounted console gear shift, it has an ignition lock cylinder control actuator system in the steering column. The ignition lock cylinder control actuator purpose is to prevent the ignition key from being turned to the OFF position when the transmission is in any position other than PARK and the vehicle may still be moving. The column ignition lock system consists of an ignition lock cylinder control actuator, and a park position switch that is located in the automatic transmission shift lock control switch. The ignition lock cylinder control actuator contains a pin that is spring loaded to mechanically prevent the ignition key cylinder from being turned to the lock position when the vehicle transmission is not in the PARK position. If vehicle power is lost, and/or the transmission is not in the PARK position the operator will not be able to turn the ignition key to the lock position and will not be able to remove the ignition key from the column.
There should be a hole in the bottom of plastic steering cover or a rubber cover that comes out . you can stick your finger up there an there is a button you push that will allow you to take out the key !
2006 chevy cobalt How to fix key being stuck in the ignition 2006 Impala shifter problems

I have seen adjusters on the console shifters for GM. You have to remove the handle and pull the bezel and boot off the shifter. Where the cable is mounted to the bracket/ floor, there is some adjustment. But there isn't enough to adjust for what your's is doing. This adjustment is for the shifter handle more than an adjustment for the range. The only thing I can think of is that the shifter arm on the transmission isn't in the right position, mounted to the transmission.. Any thing else wouldn't work.

Is it possible the transmission was not made for a Mustang ?
With the shifter on the floor, the linkage would be different than a car with the shifter on the column.
Have you contacted the company ?

I only have 2003 Nav procedure. Maybe get used part at car-part.com. Page with * is lowest price.

SECTION 307-05: Automatic Transaxle/Transmission External Controls 2003 Expedition/Navigator Workshop Manual
REMOVAL AND INSTALLATION Selector Lever —Floor Shift Removal and Installation

1. Lift the floor shift PRNDL bezel.

1. Disconnect the PRNDL bezel wire harness connector.

1. Remove the shift lever handle and cover.
   1. Slide the handle bezel down.
   1. Remove the screw.
   1. Disconnect the TCS wire harness.
   1. Lift assembly from the shifter lever.

1. Position the window regulator control panel aside.

1. Remove the screws and the console finish panel.

1. Remove the left side console access panel.

1. Disconnect the transmission shift cable from the transmission selector arm.

1. Remove the transmission shift cable retaining clip from the floor shift mechanism through the console access.

1. Remove the four bolts retaining the floor shift mechanism to the floor.

1. Disconnect the floor shift mechanism wire harness connector.

1. Remove the floor shift mechanism from the console.

1. Remove the brake shift interlock actuator, parking brake release mechanism and harness.
   • Remove the wire harness retainers.
   • Remove the wire harness retainers.
   • Remove the two screws retaining the brake shift interlock assembly.
   • Remove the two screws retaining the parking brake controller.

YES THE PART THAT IS BROKEN IS MOST LIKELY A WHITE PLASTIC PIECE THAT SITS INSIDE THE SHIFTER HOUSING, REMOVE THE SHIFTER HANDLE REMOVE THE WHITE PLASTIC PIECE WITH ALL THE ROUND BALLS ON IT (I KNOW WHAT IT LOOKS LIKE YOU DONT HAVE TO SAY IT) AND LOOK DOWN THE HOUSING WITH A FLASHLIGHT IF YOU STILL SEE A PART OF THAT WHITE PLASTIC PIECE, THATS YOUR PROBLEM. YOU CAN EITHER REPL SHE SHIFTER LEVER P# 52078551AG OR SEARCH THE JUNK YARDS FOR THAT PART