1987 chevy blazer 350 serpintine belt and v-belt. anyone know what neck is on my water pump so i can get an alumnium pump ??? thanks guys appreciate the help bubba

 

im bumping this one cause i would like to know as well i have a friend that just got a k-5 same specs and wanted one

 

The old short vs long question... Best bet is to measure the distance from the front of the block and then compare to waterpumps at the parts store.

Are your accessories mounted in front of the heads, or off to the sides? Typically if mounted in front of the heads, then it will mostlikely be a long water pump, but again, sometimes there are combinations that defy logic. GM was inconsistent with many mid year changes that make it a pain to determine what is actually in there.