I started doing a little sniffing around various trainsmission sites. I found this one http://www.5speedtransmissions.com/ that sells some cool stuff for T56 6 speeds. So I started to wonder what the Pros an cons are of the 6 speed. Specifically how do the T56 6 speed trannys stack up to the TKO 5 & 600. Seems to me the T56 6 speeds are pretty easy to come by.
SO please provide any feedback.

I love my TKO500 5 speed. Many love thier T56's. The main difference is the .5 OD sixth gear. At least with my combo, I couldn't use it. The other difference is the size, t56 is a big mutha. If I had an LSx motor, the t56 was born there, so to speak.

I installed a TKO500 5-spd (5th gear= .68 over drive) and it is far superioir to the top loader 4-spd I removed from my 68 Mustg fstbk. My Gen IV vette has a 6-spd (6th gear= .50 over drive). Overdrive transmissions are designed for intergalactic travel. Don't plan to accelerate much in 6th!

i have neither, but after alot of daydreaming and researching the 'what ifs', i came to the conclusion that the 5 speed was the way to go, if i were to go with a stick.

designed for intergalactic travel
LOL!!
The next time I drive to mars Im driving my bird (hope I have the t56 in by then, just need to sell the 700r4 thats in the bird now)

I picked the t56 because it costs so much less than a tko
There are a few more issues to deal with, if you want to use a manual clutch linkage you need to get a stock bellhousing and a spacer from Mcleod
If you want a hydraulic clutch get a McLeod scattershield.
EIther way you need a 26 spline clutch disc and extended pilot bushing
You have to deal with the shifter being further back than stock (basically just cut another hole in the floor
And the t56 only has an electric speedo hookup, so get an electric speedo or a converter

I think there is one more thing but I cant remember

But overall the issues are minor, they just need to be addressed before the install

I have a TKO 600 and love it. And as far as acceleration in OD, when in the 65+mph range, the .64 pulls better than my daily drivers. And as you get over 75-80mph, it gets stronger.

As far as the t56 sitting back further, I was a renegade and chose NOT to turn the TKO600 180* like you're supposed to. I absolutely love it being closer, and it feels MUCH more natural than in the suggested "normal" position. I had to cut my tunnel about 1". In fact, on a drive today, we were talking about this very subject, and my passengers said they couldn't imagine it being much more forward. So even not knowing anything about the t56, I'd say this isn't necessarily a drawback.

I installed the TKO 600 w/.064 OD with 3.73s and it's a real joy to drive in all respects. I think that the 6spd., because it has another gear, sounds like it may be more appealing/better to many but the question becomes is that another gear that you'll actually use? I don't drive over 125mph for any extended periods of time (hardly at all for that matter) so would not need this gear. I like the 5 gears in my 5spd. and the way they transition between each other and not missing anyting on the hiway either. As I understand the TKO 5s are built more heavy-duty than the 6spds. - reserach that for yourself though. Maybe if you had something higher than 4.11s in the rear, then the 6spd. would be useful. Or if your thinking about taking it to the Salt Flats for a top speed run.

I installed the TKO 600 w/.064 OD with 3.73s and it's a real joy to drive in all respects. I think that the 6spd., because it has another gear, sounds like it may be more appealing/better to many but the question becomes is that another gear that you'll actually use? I don't drive over 125mph for any extended periods of time (hardly at all for that matter) so would not need this gear. I like the 5 gears in my 5spd. and the way they transition between each other and not missing anyting on the hiway either. As I understand the TKO 5s are built more heavy-duty than the 6spds. - reserach that for yourself though. Maybe if you had something higher than 4.11s in the rear, then the 6spd. would be useful. Or if your thinking about taking it to the Salt Flats for a top speed run.

What ar eyou rpms @ 65-75-80? Would a 6 speed help the MPG you think?

Here is the data I have accumulated over time. While slightly specific to my application (mostly tire OD), you can get the idea. This info may help people based on what they want to do (already own the trans, already have the rear, etc). If I get time I'll simplify my excel file and post it up. Right now it is only 'me' friendly LOL.

In short, the more I learn about cars the more I realize it is all about system setup. You have to look at the whole package. In this case trans gears/rear gears/tire od/packaging. Effective 1st gear ratio is as important as final ratio. As I have been told, the rule of thumb is to keep (1st Gear X Rear Gear) between 10 and 11 (at least for street cars). At the bottom is that calculation as well.

I’m doing the T56 because I have one. Otherwise I’d lean towards the TKO600 since the packaging seems cleaner and it better matches my rear gears (3.73 now, 3.90 waiting in the wings) then a 500. I’ll be doing this swap this winter and well document it as well as I can.

Application 1st 2nd 3rd 4th 5th 6th
------------- ---- ---- ---- ---- ---- ----
TKO500 3.27 1.98 1.34 1.00 0.68 x
TKO600 2.87 1.89 1.28 1.00 0.64 x
94-02 F-Body 2.66 1.78 1.30 1.00 0.74 0.50
ST-10 (77 Z28) 2.64 1.75 1.34 1.00 x x

-------------------------------------------------------------
High Gear RPM @ MPH Tire OD: 26.6 (245/60/15)
-------------------------------------------------------------

3.42 50 55 60 65 70 75
---------- ----- ----- ----- ----- ----- -----
TKO500 1,469 1,616 1,763 1,909 2,056 2,203
TKO600 1,382 1,521 1,659 1,797 1,935 2,074
93-02 F-Body 1,080 1,188 1,296 1,404 1,512 1,620
(T56 5th) 1,598 1,758 1,918 2,078 2,238 2,398
1:1 4-Speed 2,160 2,376 2,592 2,808 3,024 3,240

3.73 50 55 60 65 70 75
---------- ----- ----- ----- ----- ----- -----
TKO500 1,602 1,762 1,922 2,083 2,243 2,403
TKO600 1,508 1,658 1,809 1,960 2,111 2,262
94-02 F-Body 1,178 1,296 1,413 1,531 1,649 1,767
(T56 5th) 1,743 1,918 2,092 2,266 2,441 2,615
1:1 4-Speed 2,356 2,591 2,827 3,063 3,298 3,534

3.90 50 55 60 65 70 75
---------- ----- ----- ----- ----- ----- -----
TKO500 1,675 1,842 2,010 2,177 2,345 2,512
TKO600 1,576 1,734 1,892 2,049 2,207 2,365
94-02 F-Body 1,232 1,355 1,478 1,601 1,724 1,847
(T56 5th) 1,823 2,005 2,187 2,370 2,552 2,734
1:1 4-Speed 2,463 2,709 2,956 3,202 3,448 3,695

4.10 50 55 60 65 70 75
---------- ----- ----- ----- ----- ----- -----
TKO500 1,761 1,937 2,113 2,289 2,465 2,641
TKO600 1,657 1,823 1,989 2,154 2,320 2,486
94-02 F-Body 1,295 1,424 1,554 1,683 1,813 1,942
(T56 5th) 1,916 2,108 2,299 2,491 2,683 2,874
1:1 4-Speed 2,589 2,848 3,107 3,366 3,625 3,884

Rpm = mph x gear ratio x 336
-----------------------
Tire diameter

-----------------------------------------------
Effective 1st Gear
-----------------------------------------------
3.42 3.73 3.90 4.10
----- ----- ----- -----
TKO500 11.18 12.20 12.75 13.41
TKO600 9.82 10.71 11.19 11.77
93-02 F- Body 9.10 9.92 10.37 10.91
1:1 4-Speed 9.03 9.85 10.30 10.82

found an real interesting discussion here
http://www.pro-touring.com/forum/showthread.php?t=32177&highlight=t56