So, for the (currently 107) people who have viewed this thread, I wanted to post the conclusion. I finally got the alternator in and compared them side by side (free shipping means 10 business days apparently). Here is a comparison of the original 90A compared to the 143A (attached photo). As you can see, the body of the 143A alternator is larger than the underpowered 90A, but the space between mounting bolts is the same and it is oriented the same way. I didn't take a pic, but on this alternator, the B+ and the other lead are reversed. There was more than enough slack in the wiring for me to reverse them without a problem, however. I don't know if the increase in size of the alternator would be an issue for turbo models or anything after my 96, but there was enough room for the larger case in the 96 e300. Next, some helpful info I wish I had had...

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