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Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by Curky, May 1, 2012.

  1. SurrealOne

    SurrealOne Former Member ROTM Winner 1000 Posts

    I third the 4.10 swap. It may be unintuitive that you can get better mpg with shorter gears, but you can. Key to this is the fact that with shorter gears on inclines you can often stay in overdrive (or a higher gear) without downshifting to ascend said inclines.

    People told me I'd lose mpg with my 4.56's (with 34.3" tire diameter) but when I changed from 3.73's to 4.56's I gained ~1.2mpg combined (hwy/city). I saw an increase of closer to ~2mpg on the highway, largely because I don't drop out of overdrive at highway speeds unless I'm in steep hills or the mountains. On the flip side, mpg goes south really quickly if I travel more than 70mph ... which I seldom do.

    Food for thought.
  2. Curky

    Curky New Member 1000 Posts

    I took a picture of the code tag. For some reason I could not up load it here. I put it with my truck pictures in my profile. I did not see that code
  3. mfleetwood

    mfleetwood New Member ROTM Winner 1000 Posts

    Sorry to hear....I was really hoping you had it already.
  4. Curky

    Curky New Member 1000 Posts

    Did you take a look at the picture?
    I could have missed it. It would be pretty cool if I did.:rofl:
  5. 07XCSB

    07XCSB New Member 1000 Posts

    Since you don't have a factory G80, you might want to think about an aftermarket locker. You could also see if you can find a complete 4.10 G80 rear from a Z71 at the junkyard. That might save you some money that way between gears and locker.

    I looked at your pic, You didn't miss it.
  6. Curky

    Curky New Member 1000 Posts

    To swap it out, would I just look for a Silverado rear Axle with 4.10 and posy 2008 and up. I have no clue on my options. Remember I’m not stupid just not a mechanic and new to trucks.
  7. mfleetwood

    mfleetwood New Member ROTM Winner 1000 Posts

    I just checked and it is not there. It would have been next to your GU5. Originally, I did not check your pic as I am sure if it was there, you would've caught it.
  8. Curky

    Curky New Member 1000 Posts

    Thank you. You have been a great help. That is what my plain will be at this point unless something changes.
  9. 07XCSB

    07XCSB New Member 1000 Posts

    We know you're not stupid. Everyone had to start somewhere. 07- up would
    be a direct bolt in swap.
  10. mfleetwood

    mfleetwood New Member ROTM Winner 1000 Posts

    Yes... you can either have a salvage yard provide you the RPO codes or you can look up RPO codes by VIN. You will be looking for RPO codes G80 (locking diff) and GT5 (4.10 gears).

    RPO VIN decoder link: http://www.decodethis.com/

    To be clear though, the G80 is not a posi rear end. It is a limited slip with a locking function.

    ---------- Post added at 01:06 PM ---------- Previous post was at 12:50 PM ----------

    X2 on that....you should see my early posts...in fact, I had many of the same questions regarding differentials as you Curky when I was trying to decide how to improve mine. That's what this forum is here for.

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