How can I tell what rear end I have?
Determining the type of rear end in your vehicle can be important for maintenance, repairs, and upgrades. Whether you have a standard open differential, a limited-slip differential, or a locking differential, there are a few key ways to identify what's under the rear of your car or truck.
Inspect the Rear Axle Housing
One of the easiest ways to identify your rear end is to look at the rear axle housing. The housing will typically have some identifying information stamped on it, such as the gear ratio, differential type, or even the manufacturer's name. This information can usually be found on the driver's side of the housing.
Check the Differential Cover
Another place to look for rear end identification is the differential cover. The cover may have the gear ratio, differential type, or other details stamped on it. Removing the cover may also allow you to see the internal components of the differential for a closer inspection.
Measure the Axle Shaft Diameter
- The diameter of the rear axle shafts can provide clues about the rear end type. Heavier-duty rear ends typically have larger axle shaft diameters.
- For example, a 7.5-inch Ford rear end will have 1.00-inch diameter axle shafts, while a 8.8-inch Ford rear end will have 1.19-inch diameter shafts.
Measuring the axle shaft diameter can help you determine if you have a standard, heavy-duty, or high-performance rear end.
Consult Your Vehicle's Documentation
If you're still unsure about your rear end, check your vehicle's owner's manual, service records, or other documentation. The manufacturer may have specified the rear end type when the vehicle was new.
Properly identifying your rear end is an important first step in maintaining, repairing, or upgrading this critical component of your vehicle. By following these tips, you can determine the type of rear end you have and ensure you're taking the right steps to keep it running smoothly.
How can you tell the difference between a 3.73 and a 4.10 gear ratio?
There is only a 10% difference between 4.10 and 3.73 gears. Unless you need to tow heavy loads, I would keep the 3.73 gears. Or maybe if you are going to big, big tires. Otherwise you probably won't notice the difference. And, If you get some big tires (35-37``) you probably would want to go to a 4.56 or so ratio.
How do I know what rear end I have?
If the ID tag or stamp is missing or unreadable, differentials can be identified by the number of cover bolts, the distinctive shape of the cover, the number of ring gear bolts, and ring gear diameter. They can also be identified by whether the center section is an integral or dropout design.
How to find rear end gear ratio by VIN?
You don't. That information is not contained in the VIN, UNLESS a specific model only gets one rear end ratio. VIN tells country of manufacture, vehicle make, class, engine type, size, date of manufacture, plant and serial number. That is the ONLY information contained by the VIN.
How do I know if I have 8.8 or 9.75 rear end?
On the passenger's side upper and lower corners, there's two semi-circular divots that can easily be seen when looking at the cover from straight on. While the Super 8.8's cover has a bulge for the ring gear, it's not anywhere near as pronounced as the 9.75's.
How do I identify my Dana rear end?
The most accurate differential identification is provided by the bottom line of the tag number or axle tube stamp. Differential tags can easily be used to identify Dana and Ford differentials.
What gets better gas mileage, 3.73 or 4.10 gears?
To keep it simple, if you want a daily driver and want to save a little on fuel and you care about performance but don't want screaming RPM, then taller gears like the 3.73 ring and pinion are the way to go.
How do I know if I have a 7.5 or 8.5 rear end?
The 8.5s and 7.5s look remarkably similar, so you'll need a measuring tape to confirm. You can also check the RPO code list in the glovebox or trunk lid for the original rear, but you still need to verify the actual housing itself since it is easy to swap them out.
How do I tell what size my Chevy rear end is?
Identify your GMC or Chevrolet rear end gear ratio by the RPO Codes, usually located on the placard labeled “Service Parts Identification” inside the drivers door panel or glove box. Note that using the RPO code for parts identification assumes that the rear end has not been previously modified!!
How to identify an 8.8 rear end?
Almost all 8.8s—and all post-1986 Ford rearends—have letters and numbers. The first number refers to the plant where it was built, and the next three refer to the ratio and type.
How can I tell what my gear ratio is?
I have my buddy holding the other Tire. I start spinning this and I'm watching the other. One. That's one full rotation right there.
