Greetings people!

I've seen a lot of builds being made with whole swaps, like putting an whole M5 in a tubular chassi and a 240z carcass.

So I would like to understand if its possible to swap any kind of rear axle into a car.

More specific, I have a E12 and was thinking to use an E36 or E34 rear axle to help improve braking and suspension, and fix a problem with Diff that I have (too short ratio of 4.11 and no speedo reading, which would be fixed by this), but no one knows if it would work, so I wanted to know if anyone did some crazy stuff like this.

I understand that it might sound really stupid, but the maintanence and reliability of those rear axles would improve a lot here where I live. And I'm also open to hear other ideas as well!

I think I should try to match the width of the axle and try to use the same mounting position, right?

Sorry if this is too stupid.

Thanks!