How to tell if differential is 3.38?

[Armo95]

Just as the topic suggests...how many different ways/methods are there to check to see what diff you have.

(I just purchased a 3.38 and I'm wondering to tell if it's really a 3.38).

Thanks in advance guys,

[Erik@EDGE]

didn't I answer this somewhere else? First off, 3.38 LSDs only came in 96-99 M3 Automatics. Second, LSD can be determined by a green painted "S" on the top of the case. You can also tell if you turn one of the flanges and the oppisite flange also turns in the same direction.
There should be a tag on one of the top bolts that has stamped numbers on it. Should read S3.38xxx or something to that effect. First letter "S" indicates LSD, the number combo after it indicates the ratio

[Erik@EDGE]

No worries, might have been a different guy. I spend too much time here!

Oh yeah...Just say "no" to the Must-Accord. Like the worst of both worlds!

[Erik@EDGE]

I am pretty confident the car will break in half

[Croak]

~3700 RPM at 80 mph on my 3.38 in 5th gear.

Not all units still have the plate on them, or a visible S.

[jterp]

The old fashioned way to measure the ratio of your gears is to jack the car up, lay undeneath and spin driveshaft. While doing this, count the revolutions of the tire. If your dif is a 3.38 then the tire will spin 3.38 times.