My '99 SE had a white impeller, I've read that the white impeller is the fix from Ford. My SVT just turned 41,000, going to change it soon. White or black its still plastic.
With all the documented failures and the damage it could cause, you should do it, especially since you have 70K on your car. Waterpumps can have problems other than broken impellers, seals and bearings come to mind!
NAPA Duratec- Pro is what I installed in the SE, pretty easy install.
