3.42 to 3.73 swap
 

I have a nice set of 1/2 ton axles that have 3.73 gears in them. I currently have 3.42s in the truck now. I have 33" tall tires and the 3.42s seem to be a good fit. Is there going to be much of a difference going to the 3.73s? I do plan on going to a 35" tire once I get around to installing my lift. I need to do some front end work to the truck but dont want to do it if im going to do this swap.

Any opinions?

Re: 3.42 to 3.73 swap
 

I wouldn't bother. Escpecially with a 35. IMO, i'd run 4.56's with 35's. If you're going to do it, do it, otherwise, do nothing, it's free lol.

= ( | 3.42 - 3.73 | / ((3.42 + 3.73)/2) ) * 100
= ( | -0.31 | / (7.15/2) ) * 100
= ( 0.31 / 3.575 ) * 100
= 0.086713 * 100
= 8.6713% difference

Re: 3.42 to 3.73 swap
 

You have the differentials. All it will cost you is time.

Re: 3.42 to 3.73 swap
 

200 RPM difference at speed. It's up to you. I'd keep em on the shelf as "spares"

Re: 3.42 to 3.73 swap
 

I did this swap and it made more difference than you would think. I went from 3.40's in my 79 to 3.73's. Mine's a 2wd on 28" tires. If you are going to 35's I would for sure since you already have them.

Re: 3.42 to 3.73 swap
 

And here I was thinking the difference was 8.67132. :)

Another way to look at it 3.73 is 9.1% more than 3.42, so RPMs at any given road speed will be 9.1% higher with the 3.73 gears.