My problem is you never know what tools to get out. My wife's Hyundai is all metric, no problem. My Ford truck is like your GMC, 50/50. All my yard equipment, you just have to try it and see what works. I've learned to never trust that "made in USA" actually means the parts were made here, as my Stihl equipment is a mix too. Used to be you could look at a bolt or nut and guess pretty accurately whether it was 7/16., 1/2, 9/16, etc. Now it could be 11, 12, 13 or 14mm.