E28 final drive on e30?

[E30 331is]

Is there such a thing?

[LJ851]

Sure, swap the back cover and output flanges and you are good to go.

[E30 331is]

so it has an e28 diff cover, but how can i tell if its an e30 diff, or is there no difference other than the output flanges and the cover? it has a white S on the body and rotates ~3.75 when i turn the output to 1Xinput.

[nrubenstein]

flanges and cover. no other difference.

[LJ851]

so it has an e28 diff cover, but how can i tell if its an e30 diff, or is there no difference other than the output flanges and the cover? it has a white S on the body and rotates ~3.75 when i turn the output to 1Xinput.

That is correct, there is no difference. If the tag is sill under a bolt on the rear cover, it will tell you the ratio and if it is a limited slip with an "S". I dont think E28's had 3.73's but i'm not 100% on that. Most E28's had 3.25 and autotragic's had 3.45.

[E30 331is]

No tag, just the white S and by rotation I figured since its close to a 3.75 its a 3.73 and since it has the e28 cover I got confused not knowing they are interchangeable. So I have a spare 3.73 sitting here... for how much these go for?

[MR 325]

Standard rate I've sold 3.73 LSD diffs for is $180-$220 picked up. These all had E30 covers and flanges of course though.