How do i identify which rear end is in my 2001 Ram sport when the tags are gone???

 

If you know it is stock, you can go here: https://fcacommunity.force.com/RAM/s/equipment-listing

Enter your VIN and it will (nearly) instantaneously spit out a build sheet for your truck which should include your rear axle ratio.

If it is not stock (or you are unsure), you will need to wait for others with expertise in this area to reply.

 

9.25 corporate rear end in 1500's. Gear ratio is open to question. Might have to pull the cover and count teeth.

 

Or go by the numbers on the ring gear.

 

Look at the sticker under the hood.

 

There should be a sticker under the hood like mentioned and/or in the glove back that shows how the truck was built at the factory. If the truck is a sport offroad it would be 4.10s

Absolute worst case scenario if you don't want to remove the diff cover you could do some calculations, take your tire circumference, ground speed at a given engine rpm against your trans gear ratio. If an automatic make sure its in drive, probably with OD locked out so you're in direct (no trans ratio needed then) and the trans will go into lockup otherwise your numbers will be skewed off

probably some online calculators thatll do it too

Could also block the front wheels, jack it up, put it in nuetral, mark the tire and go one revolution on the tire and count how many times the pinion goes around, if its over 4 then its 4.10s, slightly less than 4 3.92s (which im still not convinced even exist in these trucks I'd like to find a set) and lastly 3.5 turns 3.55s.

 

9.25 rear axles with 3.92 gears existed for sure. I sold a complete rear with 3.92 gears and limited slip that came out of a '96 Ram 1500.

 

I'm sure they do, just not where I'm looking for them lol, or maybe they weren't in 4x4s since I've been looking for a set

 

3.92's were an option, and very few people picked it. So, yeah, they make hens teeth look downright common.

 

To make matters more confusing for n00bs like me, the Parts Manual shows in section Axle,Rear,with Differential Parts,Chrysler 9.25,BE 1,6, Figure 3-210, there is this note:
And that ratio is referenced in actual part numbers:
...but in the Service Manual in the section on the 9.25 rear axle, 4.10 gear ratio does not appear as an option:
The Service Manual does show the 4.10 ratio in the specs for the 248RBI, 267RBI and 286RBI. But the drawings and descriptions of those axles & yokes do not match mine. Plus according to Der Truck in this post, 248RBI == Dana 60; so I'm assuming the other two "RBI"s are the Dana 70 & 80.