Gearing can be calculated this way:
How To: Determine the Rear Axle Ratio
Originally Posted by BrianBlair
Naturally my van doesn't have the door sticker to help me out here......the only stickers are from SMB and don't mention the axle.
What's the easiest way for me to determine what I've got in terms of gearing and diff type?
NEXT: (and most importantly for your question): Differential Type
On a van of your's age (1993), it won't have any sort of sophisticated electronic limited-slip rear axle. But it might
have an old-school clutch-pack type rear limited slip. (I think.)
That being the case --- you rear diff type can be likely
determined THIS way:
1) SAFETY FIRST --- Van OFF. Key OUT OF IGNITION.
2) ALSO SAFETY FIRST --- chock the two front wheels of the van (in both the front and rear of each tire). Do this ONLY on a level surface.
2) Lift up both rear wheels on jacks and also jack stands.
3) Try to spin one rear wheel with your hand. (May take a little bit of effort.)
A) The other wheel spins in the **opposite direction** fairly easily --- you have an "open" rear differential (no limited slip.)
B) You can't get the wheel to turn AT ALL --- you've got some sort of rear limited slip axle (with a clutch pack in the differential that prevents/resists differential action.)
If you've got a rear limited-slip axle of any sort, then as others have already mentioned you can't get away with driving any significant distance on pavement with different-sized (left-to-right) rear tires. Will overheat the differential/clutch packs and probably grenade itself within several miles, IMHO.
FWIW, my '95 E250 did not
come with a limited-slip rear axle.
(You can also look on your rear axle for the Dana BOM (Bill of Materials) number (either on a tag bolted to the rear diff cover, or stamped on the axle tube.....somewhere......) and utilize that to scour the web for the official Dana spec sheets....and then find your match to list what your axle's specs are.