TKO 600 or T-56 ?

[Tim john---]

I am considering the purchase of a TKO 600 5 speed and or a T-56 Magnum 6 speed for our car. Car is a 69 Firebird convertible that has been DSE mini tubbed and will receive a 2004 GTO LS1 engine. Car will have DSE suspension kit # 1 which includes tubular upper and lower control arms, front sway bar, 2” lowering front springs, 2” lower rear leafs, DSE offset shackles and DSE solid stock height body mounts plus DSE tuned shocks all around. Engine will remain stock and not be raced or auto crossed. Just a real nice street car and driven responsibly. Not a fan of cutting up a rust free California floor/transmission tunnel. For those of you who are running a T-56, any regrets or honestly would a TKO 600 5 speed been just fine. I am having a tough time justifying the need for two overdrive gears for a street car. It is minimal up charge for the T-56 but the floor modifications are holding me back. If you had to do it over again would you install a T-56 or the TKO 600 considering my application. Thank You for your honest opinions.

Tim john---

[Corey R.]

I spoke with Joe at D&D Performance transmission yesterday. They sell the T56 Magnum, TKO500, &TKO 600. The T56 Magnum holds more power, and shifts smoother due to its better triple & double synchro design and Carbon fiber material compared to the TKO 600's single synchro and brass material.

He informed me the T56 magnum has a smaller case than the TKO 600. There should be no tunnel modification needed in my 1969 Camaro. He also told me their T56 Magnum shifter will allow the use of the original 4 speed hole in the tunnel of my 1969 Camaro. Apparently the T56 Magnum is shorter or otherwise has the shifter located more forward over a standard T56.

The T56 Magnum also comes with a dual output tail-shaft so that I may use my stock speedometer. From the research I gathered, it would cost me another $300-$600 for the mech/elec speedo conversion if I used a standard T56. Once I add that to the $1500 for a used transmission that I'm taking a chance on a rebuild for, it just makes sense to go new.

The gear ratios in the Magnum are also more aligned with my needs over a standard T56.

Based on the above information, I will be going with a T56 Magnum.

What floor modifications are you referring to?

[214Chevy]

I'll just answer the question....LOL!!

T56 Magnum.

[Ron in SoCal]

Originally Posted by Corey R.

He informed me the T56 magnum has a smaller case than the TKO 600. There should be no tunnel modification needed in my 1969 Camaro. He also told me their T56 Magnum shifter will allow the use of the original 4 speed hole in the tunnel of my 1969 Camaro. Apparently the T56 Magnum is shorter or otherwise has the shifter located more forward over a standard T56.

Joe is a smart guy, but having owned and held both a TKO and a T56, I can tell you the T56 is a bigger (and heavier) case.



As far as shifter locations go, the Maggie has three different locations you can use to get it pretty close to factory, and there are offset shifters available as well to use with the factory console if desired.

I personally like the Maggie better for shift quality and gear ratio. I have a number of friends who have used the TKO with great success, although some experience 'notchy' shifts at high rpms.

Most first gen guys f-body guys have had to do firewall / tunnel mods to get it to fit and also be serviceable. Speedtech makes a raised tunnel piece that can be easily welded in if you decide to go this route.

Good luck,

[Ron in SoCal]

Above pic was a std T56 next to a TKO. Here's the std T56 (or the Viper T56?) next to the Magnum:

[65_LS1_T56]

Yes, what Ron said. Either T56 will require tunnel mods to get a proper driveline angle. You may consider a Legend https://bowlertransmissions.com/m/28...-transmissions
They are much closer to a Muncie in size, but bigger and longer. And they handle 700ft/lbs.

[Tim john---]

Thanks guy’s for your feedback. I am under the understanding that the TKO 600 will fit a first generation F body without floor modifications and the T-56 will require a raised tunnel, thus the aftermarket offers various raised tunnels to weld in place specifically for the T-56 in an F body first generation. I have owned a TKO 600 in the past and really enjoyed it for a street only application, not raced. I also had the HURST Black Jack offset shifter to use with the factory floor console in my 67 GTO. Our Firebird is very much rust free and I would hate to cut up the floors for the T-56 to add the raised tunnel. I would like to stick with the factory floor console in either installation as well. I understand the T-56 is stronger, smoother, bigger, longer, etc.. all good things but is all that really necessary for a stock LS1 in a street car application. The money difference is not that much so that is not the hold up. I guess to add to the initial post for the guys who had the TKO and stepped up to the T-56 in a non race application was it really worth it ? Do you find yourself actually using BOTH overdrive gears in the T-56. Thank You.

I will check out the Legend link (Thank You).

Tim john---

[silver63c10]

I'll vote TKO. We've run two of them in ours, and have been really hard on both doing both drag racing and autocross/track. We actually looked at several different options when we decided to go back to a manual last year, including the T-56, Liberty, and others before deciding on just getting American Powertrain's beefed up version.

For a cruiser with a stock LS, I doubt you'll have any of the common TKO issues. If you have a clean car, I can't see cutting it up and spending more for a touch taller overdrive and one extra gear to get there.

[Vegas69]

Absolutely hated my TKO 600. There is one good place for it, a school bus. Every t56 I've driven is leaps and bounds ahead in shift quality. Spend your money once and be happy with the results.

[DavidBoren]

I like the gear spread of the TKO600RR the best. I think it would do really well with something streetable like 3.55 rear gears.