This is the high-pressure o-ring between the oil cooler and oil cooler mount.
OEM or Equivalent Quality/Brands
Toyota Part Number(s): 90301-67004
Tach Adapter - R2
2GRFE MR2 SW20 Motor Mount - R2
Flywheel - Fidanza V6 2GRFE
Flywheel Bolts - ARP 2GRFE