my speedo has been off for about a month now and i finally got a chance to pull the battery and tray out to take a look.Turns out that the plug that goes into the sensor is bad.The black plastic that houses the actual connections to the 3 pins either corroded or melted. My question is can i get a plug off of a junk car and solder it on???, or is there a way of fixing the connector that is on there ??

If we're talking about the wiring harness side, check this thread;

http://forums.2gnt.com/dcboard.php?az=show_topic&forum=4&topic_id=91934&mesg_id=91934&page=2

It may be helpful

thats what i needed to know thanks... now just to double check, i just solder the new plug that i get off of the donor car onto my existing harness, slide some of that shrink rubber over top and i should be good to go. correct??

Precisely.