There is no real "best" transmission. Each one has it's place. For most weekend driven street-strip cars, the c4 is probably the best choice on a small block. For daily-driven cars, the overdrive transmissions are best, though more expensive. "Overdrive" refers to having one more gear--in most autos 4th. It's like reversing the gears in a rear end--a large gear driving a smaller one, and allows the engine speed to drop in comparison to the driveshaft. For instance if you had a c4 in a car, and the engine turns 3000 rpm @ 60 mph, and AOD transmission in overdrive (4th), the engine would only turn around 2000 rpm, thus giving better fuel mileage and driveability.
An AOD/E makes a decent overdrive automatic
if you're going to do enough highway miles to justify the extra cost - can be bolted in
to most Mustangs. Can also be modified to
withstand a reasonable hp level - like close
to 350 or a little less. The 4R70w's (later model, renamed /E) can easily be built to take a lot of power, and a 98-up V6 4R has
just about all the hp goodies ford has come
up with to fix the earlier models weak points and it will bolt to a Windsor. The od auto's
take about 15 to 20 more hp to turn, and of course are going to be more expensive depending on the power you want to put thru.
send your email to [email protected] if you'd like a write-up on which late models have what hp goodies stock, and what can be done to take the power you want to put thru.