"JU" is Sept. 1983, which makes sense with your head badge stamp. Likely built by Murray in Lawrenceburg TN.
It's hard telling, the sticker on the frame shows it was at a Schwinn shop on S. Padre Isl. Dr. in Corpus Christi, Texas at one point and it has somehow ended up in Indiana so I'm sure it's got some stories to tell!I find your serial number stamping interesting. Schwinn stamped their serial numbers on the bikes component prior to building a frame. So the serial numbers all had paint in the stamping. Yours looks like it was stamped after the frame was painted! That blows me away.