So now that I have verified that the clunking is coming from the diff, I wanted to make sure that I was going to get the right one for my car. I have read from previous posts that an E30 diff will go right in, is that the case. I know that I will be wanting to look for a lsd, but what gears would be to low for a automatic in my car?? Seen a few with 390 and 410, and was wondering where this would put me at speed wise or if I need to stay with a higher gear ratio to be able to drive on the highway. Thanks for any help, hoping to order diff on Monday.