I had an 86 van engine,a 305 I put in my 79 C10,it had the one peice rear main seal,but still had the typical 4 bolt valve covers and V-belts,or at least one V belt and a serpentine if I remember right (altenator was serpentine and P/S was v belt I think)..
I guess 86 was a "trasition" year,kind of an orphan..the 87 up engines had the newer valve covers with the center bolts..and sepentine belts..