What is the difference between the long style and short style water pumps for the SB 350? Is the difference in the impeller shaft length, pump housing width, or both. What is the cutoff year for the use of each? I need clarification because I went to replace my water pump on my 72 K5, got a remanned unit from a local parts store, put it on, and found that the belt pulley now sits about 1/2 belt width farther out from the engine (belt will not align around fan, crank and alt). The pump housing itself mounts with almost no clearance between the timing chain cover, just like the original. The pump housing itself looked identical as well. Unfortunately, I turned the original in for a core refund, so I cannot compare them again. Did I just get a POS remanned unit with an impeller shaft that was not properly installed, or did I get the wrong pump? Any info much appreciated.