Few will remember this, but actually the ORIGINAL Sterling kits (c.1950-1954) weren't that bad. In that era, I built several Ringmasters and Yaks, plus a couple of their 'C-series' scale kits (Waco; Mr. Mulligan). During those years their balsa was pretty decent, and they used nice plywood...as opposed to that dark, stringy, mahogany-like cr*p seen in later kits.
Sometime around the mid-to-late 1950s things began going downhill. Balsa became more suitable for building a coffee table, and overall QC became lax. Generally, any Sterling kit produced after 1960 has 'value' only as a collectors' item. That Great Lakes Trainer is among the worst.