s3.73

[E30nate]

so i just picked up a s3.73 diff out of a 1987 325is with a five speed. i have a 1991 318is. would this diff fit in my car, or should i sell it. i know the gears are different, which is sort of what i wanted to improve fuel economy. anyone have any info?

[StereoInstaller1]

Phase 1: Install 3.73 LSD to improve fuel economy
Phase 2: Install M/S50 to reduce fuel economy

All in all, a great plan.

Oh yeah, welcome to R3V.

Luke

[E30nate]

so this will fit? i got it from pick-n-pull, so should i put new seals in it, or do you think it will be ok. i was thinking i should replace them anyway. it looks like they are seeping a bit.

[E30nate]

s3.73

im still needing to know if this will fit in my car, or if the 318 and 325 diffs are different. i know the m10 cars have a small case, but do the m42 cars as well?

[MR 325]

The M42 does have the small case but contrary to what a lot of people say, that 3.73 will fit right in.

Stock is 4.10 in that car by the way.

[Teaguer]

Yes that 3.73 will bolt right in .
No need to swap anything for it to work .

True the MPG will increase but your acceleration will suffer a great deal with that ratio .

[E30nate]

the car is my daily driver so acceleration doesnt really matter. i drive 120 miles a day on the freeway, so mpg is more important.

thanks for the help.

[E30nate]

so i pulled the cover and axle flanges on this diff i got, and it looks like the axle flange seals are leaking. where can i get some good quality replacement seals for it? should i also replace the dust covers on the flanges too?