I want to install the Garhauer E-Z Glide adjustable genoa car system. I need to know the thickness of my 1 1/4 inch t-track. The choices are 5.1mm, 5.5mm, 6mm. Because of the ball bearing system, the tolerances are small. Before I look for some calipers to buy or to borrow somewhere, does anyone know this answer or where to find it?