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hotpep1's avatar
hotpep1
Explorer
Jul 23, 2014

Can Change 3.55 Gears to 3.73?

Without getting into all the specs. of my 2007 Ford F-150 King Ranch (we'll do that another day!), how big a deal (and how costly) is it to change the 3.55 gears out for 3.73's?

Thanks,
Carol

2007 Ford F-150 King Ranch Supercrew
2008 Coachmen Captiva 288FKS

14 Replies

  • Thanks for the input! No, it doesn't sound like it's worth doing...

    Carol
  • Figure about $700 per axle if you have 4x4.

    But, a change from 3.55 to 3.73 is not very much and I'm sure you are just looking at the difference in "tow ratings" between the 2 gear sets...

    Yes, the 3.73's give a better 'tow rating', but you still have the same payload and other weight limits on the truck, so it's not going to be a proportional kind of thing all around.. ;)

    The actual difference is only a couple hundred rpms in direct or even OD between the 2. I had 3.55's on my 97 F150 and thought about changing to 3.73's, and while it would have been 'better', I would have had to do 2 axles (4x4) and the cost just did not justify it for me..

    If you are really looking to be able to use different trans gears while towing for example, being able to hold OD better, or being able to stay in 3rd instead of shifting to 2nd on the smallest of grades, going to 4.10 would be a bigger change that you'll actually be able to feel and use..

    That's just my opinion on the deal, and there are some that have done the 3.55 to 3.73 change I'm sure that are happy too...

    But, like I said, if it's just to get to that magical "tow rating" figure... I'd not waste the money.. ;)

    Good luck!

    Mitch
  • I don't know what it would cost (probably $1000), but I can't imagine that little of a change would make any practical difference.

    Good luck!
  • If it's only 2 wheel drive and you have some mechanical ability the price will depend on what you can get a differential with 3.72's from the local junk yard for.