I think it's an 83 or 84 Murray built Schwinn. Some excepts from research on this:
"It is easy to identify the Murray built Schwinn frames. They have thinner chainstays and no seam on the bottom bracket shell."
"I'm very familiar with both the Chicago and Murray built frames, and you can clearly tell the Chicago EF frames apart from those built by Murray by the bottom brackets. The Chicago built frames have the slag rings on the chainstays near the bottom brackets plus the seam on the lower part of the bottom bracket, while the Murray built frames do not."
"After looking at those two Cruiser pictures I noticed another little detail between the Schwinn, Murray and Taiwan frames. Schwinn's cantilever tubes are flush with the front of the downtube. The Murray's Schwinn frames appear to have the cantilever tubes past the front of the downtube and the Taiwan frames have the tubes a little bit short of being flush with the front of the downtube."
"Schwinn made a deal with Murray to build some Schwinn models, low end lightweights and Cantilever bikes using Schwinn's parts, and their EF tools. After the two or so years the bikes Murray was building for Schwinn were then produced in Taiwan. I'd guess that Cruiser was built in the states but not by Schwinn. It still has the rear guard mounting tab on the chain stay (Taiwan on the seat stay)."