S1 main chassis box section - dimensions?

[magpies]

any one know the thickness of the 60 x 40 lower chassis box section - mine is twisted and I need to buy a length - I believe it is ERW spec

[CTE]

Drill a hole in it and measure it...I guess it`ll be 1.5 - 2mm...as for ERW, I`d have thought it would be a structural grade, although I doubt the stresses are very high.