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Need a quick opinion or two on the 3.08 rear


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Living in the "flat lands" of "The Peoples Republik of Illinoiz"; I can say this for sure...................I wouldn't want the 3.08 rear in my truck. The 3.42 rear is almost TOO LOW here when trying to maintain 65mph going up any incline!!! The 3.42 is great when running 75-80mph.................but that ain't doable on most Interstates here in Illinoiz running 65mph where the coppers need quota fillage!!!

 

Nothing I hate worse than being on cruise control cruising along at 65mph on the I-roads; and hit an overpass, and have my truck downshift into 5th!!!! Not much of an incline on the overpass either!!!

 

I cannot imagine how much worse that'd be in the mountain area where the OP lives!!!!!

 

Just saying.

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Pics or it never happened lol

I need to get a few taken, hope the weather is nice tomorrow and I will dig out my camera.

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I had a 2013 1500 with 3.42 and found I was inventing new swear words about it. My 2015 2500 with the 6.0L and 4.10 does a much better job, and only gets about 1 mpg less overall average than that 2013 1500 did. With a 1500 that weighs in at 1000 lb less than a 2500, even 4.10 would deliver respectable mpg. Many, many fleet studies have shown that the driver alone accounts for over 33% of improvement or degradation of fuel economy. And lower RPM's that is typical at cruising speeds with something like a 3.08 will not necessarily deliver better mpg than something like 3.73 on anything except flat ground with no load and no wind. If an engine is below it's optimum RPM, it takes more fuel to generate a level of power needed to maintain speed than if the engine is at a slightly higher RPM. Rotational inertia is being fought against at those low RPM's. The low RPM / better mpg thing only works well in a perfect world where there is no other traffic, no hills, no wind, etc. You know..... like a testing area at the OEM.

 

For almost any purpose, I would recommend getting the largest ratio differential you can. For me, I will never buy another gas powered pickup with anything less than 4.10. That ratio has served me well for several decades. And I became even more aware of that after making the mistake of buying a pickup with 3.42. Since that isn't really a OEM option in the 1500, I would only consider one wth 3.73 since that is around still.

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I had a 2013 1500 with 3.42 and found I was inventing new swear words about it. My 2015 2500 with the 6.0L and 4.10 does a much better job, and only gets about 1 mpg less overall average than that 2013 1500 did. With a 1500 that weighs in at 1000 lb less than a 2500, even 4.10 would deliver respectable mpg. Many, many fleet studies have shown that the driver alone accounts for over 33% of improvement or degradation of fuel economy. And lower RPM's that is typical at cruising speeds with something like a 3.08 will not necessarily deliver better mpg than something like 3.73 on anything except flat ground with no load and no wind. If an engine is below it's optimum RPM, it takes more fuel to generate a level of power needed to maintain speed than if the engine is at a slightly higher RPM. Rotational inertia is being fought against at those low RPM's. The low RPM / better mpg thing only works well in a perfect world where there is no other traffic, no hills, no wind, etc. You know..... like a testing area at the OEM.

 

For almost any purpose, I would recommend getting the largest ratio differential you can. For me, I will never buy another gas powered pickup with anything less than 4.10. That ratio has served me well for several decades. And I became even more aware of that after making the mistake of buying a pickup with 3.42. Since that isn't really a OEM option in the 1500, I would only consider one wth 3.73 since that is around still.

i wish it was easier to find the 3.73s..starting to frustrate me :banghead:

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I had a 2013 1500 with 3.42 and found I was inventing new swear words about it. My 2015 2500 with the 6.0L and 4.10 does a much better job, and only gets about 1 mpg less overall average than that 2013 1500 did. With a 1500 that weighs in at 1000 lb less than a 2500, even 4.10 would deliver respectable mpg. Many, many fleet studies have shown that the driver alone accounts for over 33% of improvement or degradation of fuel economy. And lower RPM's that is typical at cruising speeds with something like a 3.08 will not necessarily deliver better mpg than something like 3.73 on anything except flat ground with no load and no wind. If an engine is below it's optimum RPM, it takes more fuel to generate a level of power needed to maintain speed than if the engine is at a slightly higher RPM. Rotational inertia is being fought against at those low RPM's. The low RPM / better mpg thing only works well in a perfect world where there is no other traffic, no hills, no wind, etc. You know..... like a testing area at the OEM.

 

For almost any purpose, I would recommend getting the largest ratio differential you can. For me, I will never buy another gas powered pickup with anything less than 4.10. That ratio has served me well for several decades. And I became even more aware of that after making the mistake of buying a pickup with 3.42. Since that isn't really a OEM option in the 1500, I would only consider one wth 3.73 since that is around still.

^this. Ive had a few 3.08 loaners and couldn't get the mpg I did out of my 5.3 3.42 or 6.2 even. It wouldnt even turn 2k rpm until 88mph. If driving 55-65 you have to use m5 or any throttle prod would initiate a downshift.

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  • 1 month later...

To really make all of this work for every scenario, it requires also being able to have selections of transmissions that offer different gear ratios along with selections in diff ratios. That is the beauty of heavier trucks. One can spec the trans, the diff ratios, and size of tires to get the exact setup that meets their specific needs to deliver maximum performance along with maximum fuel economy. Kind of like walking into a boutique coffee shop and being able to custom order that cup of coffee or latte. With what GM offers us, you get black coffee, with or without caffeine and no cream or sugar.

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