Permissible wide gage limits on 36" lines

The question of the maximum gage has been lost to history because all the documentation of the company's policies seems to have been privileged information to officials only, and lost as the companies dissolved.
But I just purchased the tool, which tells the answer for the EBT, and we can learn the answer for the other narrow gauge lines if their track gauge tool also exists.
The railroad track gauge tool was usually built to hold the rail to the proper gage when it was spiked down, but the length of the gauge was built to drop in when the width between the rails needed correction. My EBT gauge was one of two used to build the EBT and it is gaged to 36 1/4" for construction and 38 9/16" for drop in width. I will soon get the D&RGW measurement.
I would like to hear from anyone who owns an original track gauge and give us the measurement from the rail gage on one side, with the length to the end of the track gauge tool on the other end.
The drop in measurement was their design whereby the company required immediate correction. This has never been defined for narrow gauge track as it is beyond the jurisdiction of the FRA, as Congress did not define NG specifications. But for the interest of safety, we want to learn what the various companies used for the measurement over the many years of their operation.
That physical evidence exists with the Track Gauge Tool.