I use Lightwave and might try modelling your plough/plow, just to get some experience - it always helps when you have a specific goal, if you know what I mean. Sandbox tuts are good and all, but there's nothing like the real thing, IMHO.

Post more reference images and I'll give it a go, just for the heck of it...you might even get a few to pick from if HellBorn and others do the same.. :)