I think you have a choice between original equipment, which may be dangerously metal-fatigued, and new knock-offs, some of which are dangerously cheap.
My stepdad threw a fan blade on his '54. Before he could get it stopped, he threw another one and presto -- a two-blade fan. A few years after he changed out the fan, he sold me the truck and eventually I had the same experience. Happily, none of those (four!) flying blades went through sheet metal or human meat. Just whanged off the ground and frame.
Daughter and I changed it out again, and she burbled happily off into her early adulthood. Fan was still spinning along with all four blades when the truck was stolen.
I'm not a fan of thieves...
