Sheet metal gauge for Triumphs

[LaJoMor@aol.com]

Et al....
I have looked in numerous sources including Bentley's and the VTR site for 
the thickness or gauge of the sheetmetal on Triumphs (the 1968 TR250 to be 
exact)  to no avail. 
I suspect it to be 18, 20, or 22 but don't have a gauge to measure with. Does 
anyone have this info at their fingertips? 
Thanks to all in advance...
Larry Morrison
TR250 in fewer pieces in Colorado (front suspension rebuild nearing competion)