The Husqvarna/Vikings have actually gotten less tough over the years, meaning that all of them through the 2000 might be compared to Volvos (truck or car). A couple of years ago I was trying to find out which 6xxxs were maroon, and which were brown, I stumbled across a blog by a guy using his to make leather armor for reenactments. It's too bad that systemized info about their long production isn't available, at least in English.