Can I swap my 4.1 with a 3.73 on my 91 cabrio?

[SeanS]

From what I've been told, they used 4.1 (I guess it's LSD) on my 06/91 325iC cabrio Automatic trans. The pick up is fine but at highway speeds of avg. 70-75, my engine is at 3-3.5k RPM which I'm assuming is the cause of my 19.9-20.5 MPG. What would I lose besides the "quick" pick up from stop if I go to a 3.73 (LSD or not?) diffrential in hopes of being able to go faster a a lowere RPM in comparison to my 4.1 and increase my MPG. Is it a major mechanical job to swap? what kind of cost in labor? Any thoughts, comments and opinions are welcomed.

Sean

[Alpina]

this is no problem,, if you have the other diff ((complete)

then this is a 3-5 hour job ,, of course there will be minor accl. feelings but
if you are looking for mpg the 3.73 is a good choice

[markseven]

From what I've been told, they used 4.1 (I guess it's LSD) on my 06/91 325iC cabrio Automatic trans. The pick up is fine but at highway speeds of avg. 70-75, my engine is at 3-3.5k RPM which I'm assuming is the cause of my 19.9-20.5 MPG. What would I lose besides the "quick" pick up from stop if I go to a 3.73 (LSD or not?) diffrential in hopes of being able to go faster a a lowere RPM in comparison to my 4.1 and increase my MPG. Is it a major mechanical job to swap? what kind of cost in labor? Any thoughts, comments and opinions are welcomed.

Sean

I'm thinking of doing the same thing. The manual with 4.11 LSD is good for the track, but winds up too fast for the street. Let us know how everything works out if you do swap difs.