Calling E85 Differential experts!

[True-Blue]

Quick question, excluding the M, are rear differential’s interchangeable across the E85 6 pot range?

In other words, is it just the internals that differ?

I understand the impact of different drive ratio’s, what I’m trying to understand is if, for example, a 2.5 or 3.0 M54 diff is the same externally as the N52 based 2.5i Diff…. Hope that makes sense.

Thanks in advance

 

[horseless_carriage]

There was a really helpful site called bokchoys.com that had all sorts of useful info on differentials for the e46, and since our cars are form the same vintage a lot applies to the z4.

It looks like the site has been take down, but the way back machine still seems to have a copy:

https://web.archive.org/web/20181008040744/http://www.bokchoys.com/differential/faq.htm

 

[True-Blue]

Just bumping this in the hope there’s a knowledgable member who can confirm which Diff’s will physically bolt straight in?

I’ve found a couple of options for a direct replacement, but hoping I can widen the search a bit?

Many thanks.

 

[True-Blue]

There was a really helpful site called bokchoys.com that had all sorts of useful info on differentials for the e46, and since our cars are form the same vintage a lot applies to the z4.

It looks like the site has been take down, but the way back machine still seems to have a copy:

https://web.archive.org/web/20181008040744/http://www.bokchoys.com/differential/faq.htm

Thanks for this, unfortunately can’t confirm which Diffs are directly swappable from it.