voltage wiring problems

I had recieve a k 10 blazer with a working after market alpine am/fm cassete deck in it, When i took the instrument panel of which it covers the front area of the dash where the radio sits wierd, I know but it looks like i have to cut out the sheet metal to put a standard din sized deck in.

 But the wiring is in shambles i had to figure out wire for wire testing where each go's so i figured it out after 10 minutes of testing.  all were good but for some reason i can only get the alpine deck to work.

 the wiring to the speakers is no problem its the power12v+   12v- and the memory  now i dont know it somehow its regulated by voltage for the memory wire.

 im no genius but its there a way i can just rewire those so i can make my other  decks work in there, I know my deck might be bad but i doubt it ive heard you need to have 12+ 12- and memory connected in order for some decks to work,

If so its there a way i can rewire it so i can install after market deck in or a way to test the wiring to see if there is a short in the wiring a newbie here and well ill take flames too at every point every one was a newbie once thanks  please if anyone could help it would greatly appreciated

in an 82 gm the wiring should be:

• Yellow 12v+
• Black Ground
• Orange 12v+ batt/constant(memory wire)

Most aftermarket decks need to have all three hooked up to function.  Hope this helps you out.  Aksi It is just like my 87 Sub, and youhave toeither mount the decks under the dash, or cut a hole in the sheet metal where the factory deck is.  Kinda a pain, but ya gotta do what ya gotta do.