I have a 2007 Dodge Ram DRW 48re with 12,200 gvrw. How do I know if I have 3.73 or 4.10 gears?

 

Try calling a local dealer parts dept. and give them your vin#. That can usually tell alot about the vehicle.

 

Do you have the stock tires on it? What is you RPM at 70? 3.73's will put you at about just below 2k RPM at 70. 4.10's will put you at about 2150 rpm at 70.

Do you have the window sticker from the truck? If it isn't listed on the window sticker than you most likely have 3.73's.

Another solution is to jack up a rear wheel, put a chalk mark at the bottom of the tire, and a chalk mark on the drive shaft. Rotate the tire one complete rotation and count how many times the chalk mark on the drive shaft goes around. If it goes around about 3 & 3/4 turns than you have 3.73's. If it goes a little over 4 turns than you have 4.10's. Try calling the dealer first though, that's an easier solution to try first.

 

look in the glovebox. should be a sticker that gives certain specs including rear end ratio

 

Another solution is to jack up a rear wheel, put a chalk mark at the bottom of the tire, and a chalk mark on the drive shaft. Rotate the tire one complete rotation and count how many times the chalk mark on the drive shaft goes around. If it goes around about 3 & 3/4 turns than you have 3.73's. If it goes a little over 4 turns than you have 4.10's.

If you jack up one wheel only the drive shaft will turn only1.865 times for a 3.73 and 2.05 times for a 4.10 due to other wheel not turning.

 

Well, jack the other side up to then.

 

Only if you have an open diff. If you have a locker or at least a tight limited slip, you just need to rotate the tire one time. Otherwise you need to rotate the tire two turns.