Axle 410 vs 373 vs 342

I’ve recently been looking at purchasing a Suburban. I’ve found some great deals but they all have different Rear End Axles. This vehicle would be used sparingly for towing so obviously the best vehicle for MPG would be the 342 but does anyone really know what the difference (scientifically) in MPG would be with the 3 axles at different speeds. I’ve ventured some guesses, but their must be some experts out there.

Lazy Eyez

I would go with the 373 good all around 410 you will be running high rpms all the time on th highway and 342 may be a little doggy pulling

clint

depend on tire and wheel diameter. generally, if you buy a surburban, fuel economy is not an issue

The 3:73 are by far the most common, even in heavy duty trucks. I would stick with the 3:73 too. Going to a 3:42 would not gain you much in mileage IMO.

17″ Wheels, I’m within everyone on the 373 but the vehicle the wife really wants has the 410 axle.

I’m thinking at 60 MPH the 373 and 410 and pretty equal and maybe 1/2 mile better per MPG on the 342.

However, at Interstate Speeds I believe the 410 will be about 2 MPG’s worse compared to the 342.

Does anyone have a magic formula that would incorporate wheel diameter, speed, etc…?

Has anyone ever switched or replaced an axle on a vehicle. I know there are 342 axles out their cheap at the local salvage yards but maybe the labor and/or computer program loaded on the vehicle make this not economical.

LazyEyez

I sold Suburbans for about 4 years and I would definately recommend the 3.73’s (with factory 17″ wheels). Unless you are going to be pulling some serious weight, then the 4.10′ are nice to have. The 4.10’s will give you more lower end power. Forget about the 3.42’s unless you are only hauling yourself and the family and worried about 1 mpg better fuel economy.

Sorry I don’t know the formula or know anyone that has switched the rear ends out.

4.10 will give reduced mileage.3.73 is the best all around choice.3.42 will give you better mileage,but when halling almost anything,you will notice more lugging and lack of power.

If you decide on the 4.10 gear unit, and find the mileage too harsh, going to a slightly taller tire will in reality bring your final drive ratio closer to that of the 3.73’s, and mileage with it. The actual formula is dependent on engine RPM at 60MPH(or average driving speed). I would agree best overall would be 3.73, but the diffence wouldn’t be that great. Like was said earlier, if you’re driving a ‘burb mileage problably isn’t your 1st priority.

dave

Thanks guys, I decided to go with the 410. The research concluded a lot of what you all said. 1 MPG better really isn’t that much of savings when you really think about it…I’m shooting for 15.5-16.5 and if I get that I’ll be glad. Lazy Eyez

My wife has a ’04 Yukon XL with the 3:42 and I have an ’05 Suburban with the 4:10 (Z71). At 60 MPH she is running about 1600 rpms and mine is about 1800 rpms. Her truck on average is getting about 17mpg and mine is about 16.5mpg. Honestly, I can’t tell the difference between the two when I’m hauling my Rhino or my John Deere utility tractor (3500lbs). They both do fine. However, they are no match compared to my ’01 3/4 ton Suburban that I used to have with the 4:10 gears. That rig pulled like a dream but I only got
14-15mpg average. You won’t be disapointed unless your main mission is hauling a heavy trailer around. Hope this helps build your confidence.

That is really good to know.

Thanks –

LazyEyez

Very wise descion being thats the one the Wife wants!!

410 RATIO IN 05 EXCURSION 9-10 MPG…ID SAY YOUR DOING BETTER THAN ME….