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Regarding '02 3500 D/A CC 4x4 dually.

1. Was at the dealership the other day for something else and I asked the price of a tranny fluid change. The answer was "$160 and for that we change the external filter and completely power flush the transmission." So whats the scoop on power flush? I have read many times on DP - never power flush an Allison, but the GM dealership does it as a matter of routine (and so does an independent transmission shop that I asked last week). Is the "never power flush" just an urban legend?

2. Being an old-timer, I have always talked about "4-speed" and "third gear" and the "hi range" and "lo range" of gears in a 4x4 ....stuff like that.
Now when I read FAQs etc about 5-speed Allison transmissions, they are talking about upshifts and downshifts to a different "range" instead of a different "gear". How can a single "gear" be a "range"? How are "gear" and "range" related, or whats the difference?

3. The Allison FAQ says they dont recommend aftermarket exhaust brakes because they tested ONE model of exhaust brake on a D/A and it resulted in rough shifting because of lack of communication between engine/TCM/transmission. Is there a brand of exhaust brake that works well? And is it worth the price, considering we already have grade braking with our D/As? I live in the mountains with some very steep/long grades to tow up/down.

Would appreciate any and all input. Thanks.
 

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I was at the dealer last week and I asked the service manager about draining the A.T. and he said all they do is drain the tranny from the plug and repace what came out and replace the external filter
 

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Allison's web site says to NEVER POWER FLUSH the 1000
 

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I know from experience with my 97 4Runner, Toyota dealer told me straight up, Power flushes can cause damage to the tranny if something is worn. We had a slipping problem right after buying it used in 98. Come to find out, the guy we bought it from took it to a quick change the day before we took it, they drained what was in the tranny pan and filled 5 extra qts of engine oil, luckily I noticed it before we paid and the original owner took it to the dealer and had it fixed. After that, I said, just drain and fill! Chris
 

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bikerdan;1569749; said:
Allison's web site says to NEVER POWER FLUSH the 1000
I've just searched the Allison site and can't find any reference to not flushing the transmission. Can you give me the full URL to find it?
 

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The allison 1000's gear train consists of 3 planetary gear sets. It engages the 5 clutch packs in various combinations to provide 5 forward speeds. It is a 5 speed transmission, but it only has 3 "gears" .
 

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This is a qoute from the Allison web site. Maybe I mis understand it -but here it is-
Fluid exchange (purge) machines are not recommended or recognized due to variation and inconsistencies with ensuring removal of 100% of the used fluid
 

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Ya man, the power flush is not a good idea. All the quagmire is what is filling the spaces of play up. When you take this away there is free play which will result in a blown tranny.
 
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