One of my 87 GMC 4x4s has started smoking and I believe it has a head issue. I have talked to my friends in automotive machine shop business and been advised that 193 heads are crack prone. One of my friends advised me that a company called engine is casting new Vortec style TBI heads part # CH350G, They are thicker casting than OEM and my intake fits. These heads are going on a 89 4 bolt main roller block punched .020 with a 98 hyd roller cam. Anyone have any experience with these heads. Appears to me to be a big upgrade over stock TBI. I think a truck you tow with is a good place for a hyd roller.