A vane arc segment includes an airfoil fairing that has first and second fairing platforms and a hollow airfoil section extending there between. There is a spar having a spar platform adjacent the first fairing platform and a spar leg that extends from the spar platform and through the hollow airfoil section. The spar leg has an end portion with a clevis mount that that protrudes from the second fairing platform. A support platform adjacent the second fairing platform has first and second through-holes. The end portion of the spar leg extends through the first through-hole and a pin extends though the clevis mount to lock the support platform to the spar leg. A stabilizer rod extends through the second through-hole of the support platform and limits rotation of the support platform about the pin.