Just recently my Hatch lock has stopped turning, as if its seized or frozen. Is there any way to pull it out and change it without opening the hatch (and no i can not get to the latching mechanism from the inside as there is a subwoofer box in the way)

 

Nothing?

 

No remote power release? Drill it, or go tow yard and slide hammer it. Probably would try soaking it repeatedly with lock lube, powdered graphite, PB Blaster, give it a few whacks, try any other keys, etc before destroying the lock.

 

unfortunately, my car never came with power release, My car came about as base model as you could get aside from the 2.8L v6 instead of the Inline 4. Also a slight update to my situation, I decided to crawl under the hatch from the back seat and drilled out quite a big chunk of the plastic trim to get to the mechanism in hopes i could turn it from the inside, but alas to no avail. I've also doused the lock with any lubricant I could get my hands on, wd-40, pb blaster, etc. I've done everything short of heating it up with a propane torch, I'm beginning to wonder if the entire mechanism is locked up as well. I'll post an update after I try heating it up a bit

 

A lot of these cars had the power release parts even if you didn't have the option, they just left the button off, cheaper on the production line.

As you have hacked the plastic already I would cut it up and just unbolt the latch from the car.
If you can get your spare tire cover off you may be able to bend the plastic back enough to get in there and unbolt it.

you could also take a hack saw blade in between the trunk lid and the plastic trim from the inside and slowly cut the u bracket off that the latch grabs. Just tape up the saw blade to make a handle so you don't cut yourself.

Does your car have the electric pull down (I don't think 83 did) if so you could trip the switches so that it lifts it up so its easier to get to the catch.

 

My car does not have the electric pull down, and using a torch to the extent I was comfortable with, didn't yield any results other than more frustration and disappointment.

I'd like to try to keep the u bracket intact if at all possible as they're difficult to come by around me, worst case scenario though is, I'd have to travel to Chicago to get a new one. Along with a new lock etc, etc.

Also how difficult/problematic would it be to attach a third brake light to the hatch from a 92 camaro? No I dont have the hatch it came from as it had shattered while trying to swap it by myself.
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If you have a shattered hatch then you already have a replacement catch... I would cut that. If you didn't keep those parts I'm sure you could buy one from hawks etc and have it shipped to you if not. Not sure about the third brake light those are different on the birds.

Really that is your only choice cut the catch/u-bolt thing, or cut up the plastic interior piece and unbolt the latch mech from the car. I mean you could soak the heck out of it with wd-40 every day for the next week on the inside and outside but your car is going to smell like WD40 for ever and it may never loosen up enough to turn it. Any attempt to force it will damage something...

Cutting the catch is your cheapest option though...
here is a random one on ebay (I think its right for your car verify though).
https://www.ebay.com/itm/82-92-CAMAR...-/391500047666

 

I'd try using the little straw that comes with a spray lube can and shooting it thru the hole you drilled or, between the trims at the latching mechanism itself. Spraying the lock cyl is only useful if the cyl housing has froze up. Maybe also add some weight or, have helping hands push down (variable pressures), on the hatch deck while trying to turn the key. Possibly also try hitting the downward with your palms and it may help relatch or unstick the lacth mechanism. Sometimes, too, when things get a bit wore/sticky, you may need to use pliers to turn the key with just a bit more force than you can do with just your fingers. Keep in mind.. not enough force to twist or snap the key off, though. Just some thoughts...