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Has anyone put the 5-6 speed conversion valve body in their allison? Is it worth the money?
 

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Never done it before but I'm guessing it's not worth the money. They are like what 2300 dollars plus your time and labor and if I can remember they only drop about 300 rpm seems like you'd have to do slot of driving at highway speeds to pay off 2300 dollars in fuel savings. I could be wrong though.
 

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I think i have seen past threads on this, and believe everyone said it would not be worth it

X2

Been asked before and unless you drive alot of unloaded highway miles you won't ever break even on the kit.
Much better to spend the money building your transmission to hold more HP/torque IMHO.
 

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There is NO pay-back on truck mods --- the wheels, tires, exhaust, lift,and etc-- all cost, and never "Pay-Back" anything. The best pay-back is -- leave it stock and drive it.

People buy and mod their trucks, because they have $$ to spend, it makes them feel good---------- and it helps the economy!

I love my 5-6 conversion, and it does reduce the cabin noise at cruise.

Disclaimer added-- The addition of the 6 speed, probably will not give much of an increase in fuel mileage.
 

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There is NO pay-back on truck mods --- the wheels, tires, exhaust, lift,and etc-- all cost, and never "Pay-Back" anything. The best pay-back is -- leave it stock and drive it.

People buy and mod their trucks, because they have $$ to spend, it makes them feel good---------- and it helps the economy!

I love my 5-6 conversion, and it does reduce the cabin noise at cruise.

While I agree with what you're saying, I just wanted to point out that fact to those who may be looking at it to bolster their fuel economy in the hopes of lowering their overall expenses (ie ROI or "payback"). If people want to add the kit for other reasons (lower highway noise, less RPMs on motor, just want one, etc), then I certainly wouldn't discourage it provided they are well informed before putting down their hard earned money.
 

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Agreed and added a note!
 

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here's a question, lets say someone built their transmission and did the appropriate valve body mods that are required, but then they switched to the 6speed conversion, do they need to re-modify the valve body then??
 

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I don't know--but I was told the valve body does come with a TransGo Jr. kit.
 

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If ever planning to do it, wouldn't it be best to include the 6 speed conversion at the same time as doing a full rebuild? Seems like there would be considerable labor saving?
 

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I have no knowledge on this at all nor have I searched but just wondering a common sense question.

"Couldn't you just find a 6 speed Allison and put that it in"

It seems like it would be way easier unless of course they don't bolt up to the earlier models or something.

I will shut up now for I am sure that I will get slammed for asking the question...lol
 

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I have no knowledge on this at all nor have I searched but just wondering a common sense question.

"Couldn't you just find a 6 speed Allison and put that it in"

It seems like it would be way easier unless of course they don't bolt up to the earlier models or something.

I will shut up now for I am sure that I will get slammed for asking the question...lol

Short answer is no, you can't. Put in a 6spd and you will still only have 5spd. Can't swap the TCM's either because they run on different protocols. Another issue is that the TCM gets locked when you do the Suncoast 5-6spd conversion so you can't modify trans parameters with EFI later if you want to. That was really a big dealbreaker for me as well.
 

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There is NO pay-back on truck mods --- the wheels, tires, exhaust, lift,and etc-- all cost, and never "Pay-Back" anything. The best pay-back is -- leave it stock and drive it.

People buy and mod their trucks, because they have $$ to spend, it makes them feel good---------- and it helps the economy!

I love my 5-6 conversion, and it does reduce the cabin noise at cruise.

Disclaimer added-- The addition of the 6 speed, probably will not give much of an increase in fuel mileage.
haha AMEN, it makes me feel better until something happens then im pissed, then im happy again when i get to get something new.......WOW what a cycle, i love it, wife hates it

dont know much about the 5-6 conversion but if you end up getting it post what you think about it!
 

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My first post here and to an old threat at that but thought I'd share my experience. I purchased a suncoast 5 to 6 speed conversion for an 03 2500HD. Just got the truck back yesterday and have driven it twice. Everything is exactly the same except for the extra gear. I do mainly highway/freeway driving and rarely haul anything. I read the 03 duramax doesn't have enough torque for 6th gear and that it would be hunting for gears. I haven't experienced this so far. But as I said, I only got the truck yesterday and have driven about 70 miles on it. I'm liking the conversion so far.
 

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keep us posted on your driving and what you think about it. I have a 2005 HD and have been thinking of this conversion & getting the tranny beefed up at the same time.
 

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Bring up an old thread, wanting a six speed and figure it would be cheaper to do this mod than buying a newer truck.

Any help would be grateful.
 
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