By 1987, at the height of the dive-bombing metal craze, one of the remedies to enforce tuning stability was to lock the string close to the nut. This could be done with a locking mechanism just behind the nut or by locking the string in the tuning machine and minimize the number of winding around the post. One would pull the string taut through the hole in the post and then lock it by driving a pin upward using a locking screw at the back of the tuning machine. Schaller did not have such a tuning machine available. At least, not yet. But American Sperzel did and hence G&L turned to them, starting to use their Enclosed Housing Trim-Lok tuning machines. Several finishes were used: Chrome Satin (2nd style SC-3 w/ebony board), Black Satin (ASAT), or Gold Satin (‘Buck Owens’), depending on what the instrument needed. This tuning machine also uses a location pin to keep its position on the headstock stable. In addition, for this 6-in-line configuration, the post heights are pair-wise staggered with tallest posts close to the nut, the lowest posts for the B- and high-E strings. This causes the string angle over the nut to be steeper for the high-strings, even when no string tree is used, adding even more tuning stability. These Sperzel Locking tuning machines are drop-in replacements for the Sperzel non-Locking tuning machines used by G&L.