Thanks for the comments.
My frame had been advertised as a King Sting? With doubts as to its history. The Schwinn general catalogues do not include them. I hope this information I have added brings others frames to light or memories to be stirred, particularly from ex Schwinn staff or records
I find it interesting to read the 1980 and 1981 timeline on the Mombat Timeline pages ( a great source of information) but they does not mention these frames and have not been listed (probably due to rarity, also they where only sold as frames, I may have missed them if they are mentioned).
They say Schwinn made MTB`s, in particular the King Sting and King Sting 5, when in the Schwinn catalogues respective do not include MTB`s as a cycle type made, only Cruisers. The general cycling fraternity may have seen them as an MTB. Where I live we did not see MTB`s until the mddle 1980`s.
Crumbling