Might start a war here... but T56 vs Richmond 6 speed

As my first comments, I would like to say: You don't need two ods. Four gears and one cruising od is enough. How many times do you cruise and change gears? The point of an od is that you are cruising and no longer trying to get performance by either the gear ratio you are in, or changing to another gear, and so having two to choose from becomes pointless.

Having said that, The Richmond seems to me as the better box, for a beast machine. All gears except one non-overdriven, thus are stronger. Also, having so many underdrives gives you the close gear ratios, meaning smoother gear exchanges, not going from 4000 in one gear to 3000 in the next. Of course the down side to close gear ratios is that you'll be changing gears more often, which kinda detracts from the benefits the close ratios give.

Anyways, thems my opinions.

viper spec t-56 is the ultimate 6 speed.

03 cobra ones can take just as much of a beating as the richmond.

I'll go with the ROD on this one. I've been looking at the information on it and it comes in a 2 overdrive version too, which might actually be a good thing if you have particularly small rear gears (4.56 or so.) But the big thing about it is this: The T-56 won't fit with ease in 65-68 (I don't know about 69 on) stangs. An ROD will. In fact if you had a toploader or a T-5 in it, you can use the same bellhousing.

As far as strength goes, they can both take about the same amount.

Define "better".
The T-56 was desinged for computer controlled, fuel injected, "street" cars, which usually have a wider power band because the computer can adjust all relevant things (timing, pressure, inj pulse, etc) based on RPMs. While most of the "street" cars it goes in are hi perf, the designers know most aren't going to become race cars, or even driven hard. The ratios are wide, the ODs are deep (gota try to get some kinda fuel mileage), and the dimensions are bigger.

I chose the ROD because I wanted a performance transmission (not a transmission from a performance street car). It has 5 forward, close ratio gears for driving and 1 overdrive for cruising. It is lighter and smaller (dimensionally), only requiring a slight "clearancing" of the tunnel cross member (pic on request) as opposed to an entire tunnel raise. The shifter alone would have come up an additional 5" back from where the ROD did, and even with my seats moved back this would have been hard to shift (I'm not double jointed).The internals are stronger than the T-56. The shifter is more positive (no slop like the ball socket types). The available ratios gave me a better choice of gearing over the T-56's 2 basic ratios. And, at the time no one even made a scattershield for the swap.

I did the research and crunch all the numbers (gear ratio charts, dimensions for install, co$t) when I did my swap and although much more expensive the ROD was the way for ME to go. It's the ONLY way to go, just the way for ME to go.

T56

All great inputs. Let me add to the discussion.

GP is a advocate ROD and he is qualified to make a sound judgement. I wouldn't argue with any of his points as they are well stated. He made the choice based on carefull study and sound engineering. We kid each other, but it's just fun.

I Haven't seen another early T-56 installation. I can say that my installation wasn't easy. It requires a custom cross member, raising the tranny hump up 3" and widening the hump 2". In the end, the heater outlet duct won't clear the rasied hump.

As far as driving the T-56, I wouldn't recommend it for a pumped up NA car. These engines need to rev above 3,000 to make any power. You can't cruise at 1700 RPM. In my case, the two ODs doesn't matter. With 600 Ft-lbs I can accel fine in 5th and 6th. With 3:50 gears, I'm turning about 2000 at 70 MPH. With a .63 OD, It's amazing how much speed you gain for every 100 RPM increase.

In summary, due to the installation factor, I can't recommend the T-56 for most early Mustang builders. It's more fab work than most are willing to tackle.

RT

Definatly lots of fab work to fit in a classic.

The reason for choosing it was because it became an easy install to mate to the 4.6 and even recieved an aluminum flywheel and larger 11" clutch.

I agree with gp001 here. From all the articles I've read about EFI vs Carb, they pretty much made same peak power, but EFI did had better average power acress the powerband.