HELP!!!! I have to decide before spring and I have been trying to decide for about 3 mouths now! So I thought I would get some outside opinions! I can get a 4l60e cheaper but think that the t56 would have the neat factor. As far as drivability I have yet to drive a truck that has a six speed in it and have not seen any at the track run so not sure how the auto and the 6 speed times compare. I am an above average standard driver and would really like to get any opinions on what you would do? I know that the auto would be faster at the track but not so sure on the street any opinions would be greatly appriciated!!! Thanks!!!

 

well a t56 would be nice and a great upgrade for your vehicle but on the other hand


a 60e will not hold up for your application an fltlevel 5 65e (rated for about 500rwhp) might but if your going to stay automatic you should look into a 80e swap

 

heres my point on the t56 swap i want it to look factory if some how i could do it and amke the interior look stock i probably would

 

Retsell did one in an extended cab using a center console and it looks factory.

 

Yeah just put an 03-up center console in it. Stick a leather boot and **** on it and it fools everyone into thinking its factory. I kept my column shifter to screw people and to freak them out. It's kind of funny. But since you're already a 5spd you won't have to worry about it. Swapping to a T56 for you is literally a bolt on affair. An auto will be more consistent at the track and a little quicker, but not necessarily faster. With Synergy's 2 step, there's no reason why a 6spd couldn't leave just as hard as an auto either.

If I had to pick an auto to go with, starting from scratch like you, I would go with a TH400 and a gear vendors if you need OD. You wouldn't have to mess with the whole auto wiring harness issue since you don't have one to begin with.

The key factor with beating a T56 on the street and track with a heavy truck is getting a clutch to live. I have a Spec stage 3 and it's starting to slip. I didn't really think it was that great of a clutch and I've heard a lot of bad things. For your power levels now and for the future (I assume the 4.8 won't be in there forever) I'd go with a Textralia clutch and preferably their dual disc setup. Don't skimp on the clutch, you'll regret it.

 

I have just seen this post....Where have I been?

I love my T56. The only mods for a 5 speed truck is a custom driveshaft( shorter and uses a TH350 style yoke), and cutting a new hole for the shifter. Use the T56 slave and you can mate the truck clutch line to it (you'll figure it out when you get in there, it is easy). You have to have an LS1 style clutch. The tune has to be changed for the speedo to read correctly due to the different # of teeth on the speed sensor reluctor wheel. I figured it out, not too bad if I can figure it out. My cruise doesn't work though. I just haven't had time to look into it. Probably just something simple with the gear selector wiring that may need to be jumpered. I think the 5 speed has 1 more sensor on it that the T56 doesn't if I remember correctly.
The 2.62 1st gear and the .50 6th don't mix very well with the 3.73's and the 31.5" tall tires (275/55-20's). I have to ride the clutch a little too much starting off on the road and 6th gear lugs too low of an rpm even at 80mph (around 1700 rpm if I remember correctly). I will be trying 4.10's in mine. The T56 gearing was designed for cars with 26" tall tires and 3.42's.
The extended cab/ Tahoe center console mod is what I did but am unfinished with it. It works real well but you have to make your own shifter handle. I did it out of a 5/8" round bar I got from Lowes. All you need is a torch, hammer, vise and a good imagination to get it right. Here is the console mod I copied. Mine doesn't look this good yet.

LINK

 

Hay TurboGibbs , good info. I have a question . Can you power shift the t56 ? i know the 5spd. is almost impossible to shift under full throttle. I have been thinking about a t56 converson myself.
Ron

 

You can powershift the t56 Im going from auto to the t56 just for the fun factor.

I just installed 4.56 gears for 1truess in his t56 truck and he loves it. 1800 in 6th at 70mph isnt too bad at all (3.73s were at 1500).

 

I vote T56, I do not have one in my own truck......yet, but I have driven a friends GTO and it was a blast. I am going to be doing this, once warranty is up.

 

The T56's power shift nicely.