[Vwdiesel] water pumps

[MLightner]

After contacting  two different local parts houses, I've got a couple of 
questions I'm wondering about.

1).  At an O'Reilly's, the partsman said there are four different WP's 
it could be that I need, and distinguished between them either  with the 
variables  being that there were more or less bolts holding  WP to the 
WP housing,  or by a 30 or 35mm measurement of some part of them.  The 
second parts house (a decent, but pricy, foreign auto parts supplier)
said there's only one pump option.  I went and looked at the pump they 
had and the impeller is a stamped metal thing
that looks like its either crimped or spun onto the the shaft.

My questions are: 1)   is it actually possible to put a different pump 
on a 1.6 TD if you have the correct housing to go with a different pump, 
or is there only one housing that will mate up with the block?

                             2)  Judging from the recently discussed 
failure mode of the stamped-plate type of pump, I was wondering what 
some of you more experienced mechanics would think about the idea of 
extending the useful life of the pump by taking a hammer and center 
punch and dimpling the shaft at a few places around the shaft right 
where the impeller joins the shaft? 

Mike in NC