It still could be built by Myata but just to a cheaper spec that Univega/Ben Lawee wanted to make a steel price point.
The catalog doesn't give more than 9/69/ Double Butted Chromonly main frame and stays, so it may be Myata tubes if built by them or some one elses tubing.
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“One morning you wake up, the girl is gone, the bikes are gone, all that's left behind is a pair of old tires and a tube of tubular glue, all squeezed out"
Sugar "Kane" Kowalczyk