Al,
The stock 20B pump has the 2-thermostat water pump housing.  Also, the
water pump casting is longer than a 13B, repositioning the CL of the
shaft/pulley.  Enclosed is a picture of your engine showing a single
thermostat housing, so it looks to me like you are running a 13B housing

and pump.  What I don't know is if the 13B turbo uses a larger impeller
than the n/a 13B.  I have a n/a 13B pump and the impeller is .150"
smaller
than the 20B impeller.  I'll keep asking until I find out for sure.  It
looks like the 13b housings are the same.  That is based on measurements
I
took last night to see if the 20B impeller could be installed on the 13B
pump.

Just for the record, the reason I'm going through all this is that the
13B
housing is 2+ pounds lighter than the 20B housing, not sure about the
pump,
but I'm guessing it is about 1/2 lb lighter.  

Mark;

Yes, I knew it was not a 20B housing, but thought it might be a 20B
pump.  I'll get a picture of it when I get a chance.

Al