Shifting problem?
 

Hey guys , I have a manual 1986 gt 5.0 302. Not sure if I will need a new transmission ,but when i go to shift into a gear(has happened to all gears except reverse) my Lever will not go into the gear I'm trying to shift into even with the clutch fully engaged, it doesn't happen everytime, but more than enough for me to know there is a problem, I have no idea what this problem might be ?

If the clutch is engaged, then you can't shift. You have to disengage the clutch,
to shift into gear. When you push the clutch pedal down, the system uses the
release bearing, and pushes in the clutch pressure plate to release the clutch
and disengage it. Try that. Thus, when you release the pedal, the clutch is
engaged, therefore, you can't shift while the clutch is engaged. So, since you
say it is FULLY engaged, then the clutch disc is pushed against the flywheel by
the pressure plate, and locks the engine to the transmission input shaft.

That's my bad I meant to say that I have the clutch pedal pushed in all the haha not my first time driving a stick

LOL Yeah, that's an important distinction. As 08'MustangDude was saying, the clutch is always engaged, by default. It only disengages when you press on the pedal, and it re-engages when you let go.

So I think the next step should be to get under the car and make sure that the cable from the pedal is actually moving the release lever when it's pressed. You can also use a prybar while you're under there to move the release lever manually to disengage the clutch. If you can successfully disengage the clutch, the shift lever should be able to move into any gear position.

I doubt this is the issue,but you can try checking the cable adjustment by doing the following. The Foxbody has a plastic quadrant & pawl assembly at the clutch pedal,with teeth that mesh together,thats used for clutch freeplay adjustment and the cable is also spring loaded.This keeps the throwout bearing pressed up against the pressure plate fingers,adds some preload to them plus it compensates for clutch disk wear also.If the teeth are stripped or worn,it could prevent the clutch cable from maintaining this preload and freeplay on the pressure plate.So IOW,as the clutch disk wears and gets thinner,the throwout bearing moves forward on the bearing retainer to maintain contact with the pressure plate & keep preload on it,otherwise the clutch cable will get loose and youll have to press the clutch pedal down quite a bit before the throwout bearing will even begin touching the pressure plate.
To check your quadrant & pawl assembly,reach down under the dash and grab the clutch pedal from underneath,pull upward as far as it will go then release it and slowly press the pedal to the floor with your foot.Listen for an audible clicking noise as your pressing the pedal down.If you hear clicking, that means the cable was loose and in need of adjustment and what you just done adjusted it.If it did click,run through the gears to see if it helped.If it didn't click,it was either already adjusted which means something in the clutch assembly may be causing your issue or the teeth are worn,preventing the cable from adjusting properly.If the clutch has been replaced before and it was upgraded to a heavier duty clutch assembly,that can cause the quadrant/paw assembly to wear also.