I have put 90K miles on a used one W/ .70 OD and 2.9 first behind a Slightly warmed over 390. It is alot driving our service truck so I'm used to short first gear. the drop on 2-3 is HUGE so not the best for real high performance. I pulled 99.98 mph in the 1/4 mile in a light 67' mustang coupe .It stood up to some very spirited driving for years. And bolted right up! Inspect very carfully measure at least twice . They can be fun. BenVZ
I have one in a 65 Mustang with a mild 289 and a 4.11 axle. I have to admit that I have been impressed with the driveability. It is really nice out of the hole and cruising at highway speeds is very comfortable. The main downside is that I don't know of a good shifter for these transmissions. Still, I beat on it pretty hard and it has held together just fine. Of course an FE with sticky tires in a heavy car may be a different story.
That said, I just scored a Ford Racing Superduty T-5 new in the crate on Craigslist so the toploader is coming out.
The Mustang 3 speed doesn't have too bad of gear ratios, the ones from other cars with a 2.99 first gear have big drops to second and third.
The overdrive Toploader from Granadas and vans stood up OK to my 351W in a 3400lb 65 Falcon convertible but the ratios were awful. I had 3.89 gears so the .8 overdrive was nice but the drop second to third was terrible.
Shifter was easy, just turn the 3-4 lever upside down on a normal Hurst, the Hurst bolts straight to the tranny with no adapter plate.