Originally Posted by T-Mar

I concur, it appears to be boom era. While the stamped dropouts do suggest hi-tensile steel, if the TA crankset is OEM, there may be a possibility of a higher grade main triangle or at least a lightweight hi-tensile steel. The possibility of a higher grade main triangle supported by the apparent lack of top tube cable stops, unless they are hidden on the opposite side. To this, end I'd determine the req'd seat post diameter, before I declare it gas pipe. I'm assuming a metric tubeset, but it best best verify the seat tube outer diameter too.