Joe nic

Ok so ive swapped a 2002 4.8 out of a gm 1500 p/u into a 98 gm 1500 p/u. Both trucks had a 4l60e. I used the complete eng , trans, pcm & harness out of the 2002 p/u. I no longer have a working shift indicator in the instrument cluster. On the original 98 truck the trans is controlled by the computer behind the glove box. The trans harness goes to this computer. On the 2002 truck everything is controlled by the one pcm under the hood. My thinking is that the shift indicator probably gets its info from the computer behind the glove box which is no longer hooked up. I'm thinking one of the wires going to this computer will have the shift position info & I'm going to have to splice into that wire & hook it back up to the computer behind the glove box. Does anyone know what wire that is? Or if im even on the right track. This is a problem no one seems to know anything about. Any help would be much appreciated. Thx.