how do i get the lock off the spare tire if i don't have the key. the have both keys to the car but the lock wont open. is there a trick to it?

The door key should unlock it, unless the door locks have been changed, or the spare lock has been changed.
You can get the spare out in an emergency by using a jack under the tire tub, right where the lock goes on the bolt there. Jack the bracket up slowly, and then pull the lock bolt away from the bracket. You might even be able to push it up by hand, instead of using a jack...it's a little tougher that way, but it can be done. I do mine like that instead of loosening the bolt to release the tub.
hth

 Mine has a independant key! It will not fit ignition or door locks.  I am of the belief it is an after market lock. Works great.  Unless the tire is flat, you cannot get mine out by jacking the tub. It does not rattle that way.  Experience!      Mark

The earlier cars do use a different key for the spare tire lock(and the alarm, if optioned), but this is a '79, so the door key will work it, unless the door locks, or the spare lock, has been changed.

If you can't get your tire out by jacking, just reach up with a socket and U-joint and take the bracket off the frame.  Then a locksmith might be able to open it and re-key it.  If not, split it open and replace it.

Larry

the door key fits it just doesn't turn. i'll try the jack the tub up, lets see how that goes. and by the way i found the third flasher. its in the center console, to the right if the shifter. remove the side cover and you'll see it.