exploding plastic fan

my 91 explorer (new to me) has masive cracks along the engine cooling fan hub and blades (made of a white plastic) is this common on a truck this old? Looks like it may fly apart anytime it is spinning, these are big cracks all over. Are fans expensive? and is there an upgraded fan that is better (ie metal maybe?)

This fan is engine driven, not electric, looks like a rear chore to remove, any advice?

thanks

Plastics over time deteriorate with exposure to heat and chemicals. If yours is original then after fifteen years it maybe time to replace it. I have seen plastic fans disintegrate on old Volvos causing expensive radiator damage.