I beg to differ sir, I believe thrash pertains to all bands that play thrash (Metallica, Exodus, Slayer, Megadeth, Fueled by Fire, Nuclear Assault, etc etc). Crossover Thrash means punk/hardcore bands that switched into thrash/made their music metaler (Suicidal Tendencies, DRI, etc).
I know people will flame me for this but, I honestly hate Dave Mustaine. Sometimes his voice makes me want to stab my ears with toothpicks, his face pisses me off for some reason (I have redheaded friends but Dave's hair and lips just make me angry), and I dislike his poofy old fashioned shirts (Come on Dave, your in a speed/thrash metal band not classical power metal band), and frankly I'm not thrilled about his riffs or attitude.
all the bands you mentioned played "metal" and came to the party 83 or later the term THRASH was around earlier.only the first 2 DRI records are thrash after that they crossed over and slowed down.most metal bands got faster around this time.therefore crossover.
i do agree with you on mustaine,i never did get into megadeth.
Guns N' Roses formed in 85 and released their debut album in 87. They aren't "metal" they have metal roots but they have mainly a huge mix in their style (punk, metal, Classic Rock,blues).

