I found the following information from (Viking Pump,Inc)
Peanut Butter:
Viscosity ranges from 10000-100000 SSU,varying as make up and temperature. Normal pumping temperature is from 90-180 deg F. SP.Gr.: 1.1 to 1.2
Here is another value, this one from Tri-Clover. Peanut butter, 77,400 SSU at 110-140 deg F with a specific gravity of 1.2.
The value probably varies by manufacturer due to differences in product formulation, i.e. amount and type of oil used as well as the grinding of the peanut.