Shimano Deore DX would place it 1990-1993. As you've noted all the models were Coyote variants. The model with Deore DX was the Coyote Pro-4. I have price lists for 1991-1993, showing it being TIG welded Tange MTB. Prices vary from $650 -$850. Position in the line-up varied.,depending on the year. There was a full line from hi-tensile models up to Tange Prestige models with XTR in 1993. There was even an aluminum framed model but no carbon models until 1994, when they also introduced a titanium model. In 1994 the Pro-4 went to Deore LX but got a suspension fork while the carbon-fibre framed model, the Carbon 5, was Deore XT. That certainly looks like steel to me based on the fitting attachments. Price lists show the company being from Ketchum, Idaho.