My tag in the glove box says Dana 5200 and Dana 6500? The dif covers were changed before I got my truck so there aren't any tags. I would like to try and figure this out so I can order the proper parts to do a gear swap.

I have 3.55 with 37's...I am looking to go to a 4.10 or 4.56. Most likely 4.56 so I am trying to figure out if I need to chage the carriers. Is there a good person to call about this?

Thank you,

Paul

 

Your 01 auto has a D70-U rear axle with a GAWR of 6500 lbs. The carrier break happens at 4.10 for the D70-U. You have the 4.10 and down carrier now. For 4.56 and up, you will need to change the carrier.

 

Most likely you have a Dan 60 up front and a Dana 70 out back....

All 3/4 and 1 tons have Dana 60 fronts. 3/4 ton and 1 ton SRW had Dana 70 rears and 1 ton DRW have Dana 80 rears.

Hope this helps....

 

Yes, this def does help. where is the carrier break for a dana 60? Will I need a new carrier for the 60 if I go 4.56?

Thanks,

Paul

 

stick with the 4.10s.. you will be screaming with only 37s and 4.56s!

 

The D60 carrier break is the same - 4.10 and down, 4.56 and up.

 

31's and 3.55 = 1594 rpm @ 60 mph w/auto

37's and 4.56 = 1715 rpm @ 60 mph w/auto

121 rpm isn't much to get worked up about and isn't even enough gearing change to overcome the large increase in roational weight and rolling restance, nevermind the change in roll out. If performance is the reason to change the gearing, I would skip the 4.10's....it won't be enough of a change with 37's.

 

Yeah I am changing for a multitude of reasons. One, when I am driving the conv never really locks up and when it does I am only at 1300 rpms...talk about turbo lag and horrible egts. Second, I will be towing from time to time and the 3.55 will not cut it with these tires. Thrid, I like to drag race. Fourth, I want to pull with it.

I will be going with 4.56's. I have no issues with 1700 at 60

Thanks for the help! Now all I have to do is generate a parts list. Any one have a good suggestion for carriers and gears - and where to get them? Also, were all the axles the same in the D70's and D60's or do i need to find a code or something?

Thank you,

Paul

 

The only option for the front is a manually selectable locker...an LSD or auto locker won't work with the CAD front axle. For high performance street use in the rear axle, I highly recommend the Dana Powr-Lok.....by far the toughest and best performing LSD out there.

No, not all D60's and 70's use the same shafts. Your D70-U rear uses 32 spline shafts as does your D60 front. Both can be easily upgraded to 35 spline but the front isn't cheap to do.

 

The above statement is accurate for AUTO trans. All MANUAL trans 3/4 ton CTDs (98.5-02) had Dana 80 rear axle.

If you swap out the front unit bearings for the EMS manual hub kit, you can run whatever differential you like.

 

I am new to this site so hello,I have 4.10s and 37s and they are perfect IMO 2000rpm at 75 mph. I wouldnt go with 4.56 if I were you.

 

EBunger,

Welcome to the site....

Again, if performance is the priority for the gear change, 4.10 is not enough to offset the difference in roll out, rotational weight and rolling resistance that the 37's will create over the factory tires. Even 4.56's are barely enough to bring the performance back up to the stock tire level. Towing performance will also be greatly improved. For the application Thedieselkid described, moving from 3.55's to 4.10's will not be enough of a change to bring the engine back into it's best operating range.

On another note, if your tires are truly 37" tall, you have 4.10's and you have an auto, you should be turning 1542 rpm @ 60 mph and 1851 rpm at 75 mph. Either your tires are are shorter than 37" or your speedo is off.

 

You find a tire that measures true to its designation let me know.My tires are shy of 37 probably more like 36.25 but my speedo is gps accurate to 1/2 mph.If I need to I can just use 3rd gear and tow at the 50-60mph range.I like mileage cuz performance just isnt an issue.This is my true experience and 4.56s would make my truck worthless at interstate speeds.According to MY calculations 75mph=2200rpm w/4.56 in OD/ 2000rpm w/4.10 in OD 60mph=2200rpm in 3rd w/4.10s

 

My old 12V would turn 2200-2300 at 80mph all the way from PA to FL and back with no issues at all. It made towing great!! I had instant power and never had to worry about getting a good runny for the hills.

 

I run 35s and 3.55s good balance. 80MPH at 2000RPMs which is great since most of my highway is 75-78mpg.. Max gross combined towing is 38,000lbs with no issues at all. But I have a manual and 6 gears to choose from... I'm not one of those guys who thinks he needs to be pulling 30k in OD all the time...
Ave MPG with my setup is 18hwy and 14cty normally 16.5 overall.... Big sticks, 8000lbs, pretty good balance for me... whatever floats your boat!