Here's an impractical challenge. Take any 10 GT's put them up on 10 lifts and drop the rear pans on each of them. Any one of us who regularly maintain GT's can walk down the row of the 10 lifted GT's and tell you which GT has a cooler and which does not. Those cars that have a film of transaxle fluid accumulated across the bottom edge of the transaxle will be the cars that have no cooler. The cars with a dry as a baby's butt transaxle will be the cars that have a cooler. Another visual clue is up top - especially easy to see when the airbox is removed. The non-cooler equipped cars will have a much higher propensity to show fluid weeping up and out of the shift linkage shafts. The weeping fluid tends to attract a lot of dirt and so the evidence is pretty easy to see. GT's driven even moderately in 80F+ weather should have a cooler installed. If you seldom drive in warm weather and/or your GT is only driven in annual parades and such, then a cooler may not be needed. For the former category, even moderate street driving causes the transaxles to run at high temperatures. (This is compounded for modified GTs which place higher heat dissipation demands on the drivetrain - hence the reason for Ford's recommendation of a transaxle cooler prior to pulley/tune upgrades.) Anyway, the high transaxle temps tend to vaporize the fluid and these vapors escape both through the vents and through the aforementioned shift linkage seals. Hence the external film of oil. The addition of a transaxle cooler - with its inherent 20% (0.8 quarts) increase in fluid capacity substantially addresses the fluid vaporization (i.e. high heat) and the weeping will stop. At a replacement cost of $10,000 for the transaxle, it would seem that the addition of a cooler is cheap insurance. Other than a slightly lighter wallet, there is no downside to having a cooler installed on the car.