Water pumps?

[Mogman]

Please forgive me if this has been discussed before but a search did not turn up anything,
So I was checking out a company that sells water pump parts and noticed the impeller was different on the civilian 6.2L than the 6.5L, the 6.5L was slightly larger in dia. and the "fins" were laid out a little differently so the question is, is there an "improved" pump?
In the past I have rebuild most of the water pumps I needed, mainly it was much cheaper because of my odd taste in vehicles... there are a limited number of shafts and seals that make up most of the pumps out there.

 

[86humv]

There is a V belt and Surp belt water pump....the surp pump is high output, and turns opposite.
Backing plate is pump specific.

 

[Mogman]

Makes sense that they would also improve it while setting it up for reverse rotation considering that series of engine has a history of heating issues