Guys: i need some help here,as a newbie i just picked up a 2004.5 ctd 325/600 the dealer told me it has 3:73 gears and the flashy window sticker read 3;73 as well.during my return trip with the truck i read over the option label in the glove box it says 4:10 gears.now at 60 mph my rpms are on 1800.what do i have in my truck?? could the label in the glove box be wrong ? is there any other way of determining the gearing.i.e. vin decoding ?? also what does the tow pkg. give you over non tow pkg?? thks

 

I bet you have 4:10's.

 

If the label in the truck says 4:10 then it is, the RPM's sound right too, my 04.5 has 3:73 and at 60 i am running about 1650rpm, the best way to tell is mark your back wheel at top dead center, mark the drive shaft at tdc and move the truck ahead slowly until the wheel mark is back to tdc and have someone count how many rotations the driveshaft made. tow pkg has nothing to do with gear ratio, it just gives you the hitch, lights etc. you have to order a truck with 4-10 gears, there is not that much of a demand for them for dealers to keep them on the lot.

 

The best way to tell is look on the label on the axle, or is that is missing, it will be stamped on the ring gear. And it not, then you can just count the teeth and devide. 41 on ring gear and 10 on pinion is 4.10

 

As said there should be a tag on the rear end that will be stamped with the gear ratio 3.7 for 3:73 or 4.1 for the 4:10's.

 

thanks guys!!!!!

 

Mine with 3.73 gears and stock tires runs exactly 1800 RPM at 65 MPH. Sounds like you have 4.10s or very worn tires!

 

Jack up the rear end- put the truck in neutral and count how many rotations the drive shaft does to one full wheel rotation.

 

Glove box is right!

 

That is a very rough way of checking, and almost hard to figure if you have 3.73 and 4.10s.

It's fine if your checking like 3.55 vs 4.10 or a bigger variance.

 

if the tag doesn't tell you, the information is stamped on the right axle tube ..... the only info on the tag on mine was to use limited slip lube

 

You 2nd Generation guys posting about DANA axels when 3rd Generation trucks have AAM axels.Totaly differant.NO TAGS or STAMPS on AAMs showing gear ratio.Rpm sound like 4.10 with a auto.Also there MIGHT be a tag in the glove box or it will be on the build sheet.If no gear ratio on build sheet or window sticker its a 3.73. If 4.10 is listed its because it was option and costs $.Tow plow group USE to give a differant valving in the trans valve body for shifting from D to R to keep trans temps down.Quicker engaugement.Posi also.Not sure on a 3rd gen.Heck I'm in Georgia so what do I know about snow plow option.

 

Get the parts guy at the dealer to print you a build sheet. If you are going 76 MPH you will be turning 2300 RPM's if you have 4.10 gears.... Oops, your in Canada......oh well