Help! '90 4Runner Stereo Problems

So over the past few months I've been hunting for an original radio/cassette player for my 90' 4Runner because it didn't have any kind of sound system and I have a tape deck so I thought why not. The other day I finally got the last few things I needed and wired it up and all hell broke loose.

The stereo was admittedly salvaged from a junkyard nut works great with no problems... in a '94 Camry. In the 4Runner however I get nothing but static. But then when I take the exact same stereo out of the Camry and connect it to the 4Runner it sounds pretty good, better than it did in the Camry, which is strange in itself considering the junkyard stereo sounded better in the Camry then the one from the Camry did.

Then there's the added problem that if the driver door is closed even slightly the fuse blows instantly. I did some poking around and figured out the door sensor (the button that turns on dome lights and makes noises when the keys in the ignition and the door is open) has NOTHING to do with it. I tested it multiple times pushing it in and the fuse didn't blow. I even disabled it so the car thinks the door is closed and nothing, but the moment I actually closed the door, the fuses blows! Then later on I had the stereo playing and I closed the door a tiny bit so I could get around it (my driveway is very cramped) and the fuse blew again. The door wasn't even technically closed as it was still a foot/foot and a half open! This has me completely baffled. I checked the doorway for pinched wires and there was nothing. There are no explanations that I can come up with behind this.

If anyone has any ideas regarding these problems and possible solutions please let me know. Any help is greatly appreciated! Also If anyone knows whether all 1990 4Runners came with back speakers or not please let me know. It looks like I have might some (it's hard to tell and I don't know if they came standard or as a bonus option back then) but I can't find any trace of the wires for them and I really don't want to tear apart my car looking for them unless I really think they are there. Once again thanks for the help and sorry for the lengthy post!