Those are SHO SHOP pullies
i don't mind using crank udp. several years,and 50k miles...no issues's:shrug:
I wouldn't use any crank pulley that did not have dampener construction. The seals on the front crank is susceptible to leaking. There is stories that the Duratec needs this dampening from causing damage.
There is an explaination in the British American Transfer catalog. BAT is a performance parts supplier.
http://64.202.180.37/files/contour.PDF