Would running over this really hurt my truck?

Okay so you've seen them big oil barrels, or barrel racing barrels, well cut them into four pieces equally. I ran over the end of one with my pickup. Flat out strait over stradled it. Tall gr, checkin cows, didn't see it. Well its a 1990 Chevy silverado, shortbed, regular cab, 4.3 liter V6. When I ran it over my truck blew a head gasket. I didn't hit it fast, I was crawling less than 5mph and went over it all the way. Its engine has been rebuilt twice now in 2 years and a new transmission. Basically the thing has been nothing but problems since i've had it, and its had A LOT of work. Some crazy mechanic said it was just my cadillac converter messin up so I took it to my college ag shop and cut it off and had the guys up there look at it and they found the real problem. Blown head. Every mech i've called has called it a hopeless cause and not worth fixing, so i'm gettin a new one and sellin this one for parts or whatever. I'm just makin sure the guys at the shop aren't bein nice and tellin me it wouldn't cause this. So ya, answer me truthfully! did it hurt my truck?