Is there a 3 point steering wheel that was used on most 86-87 635's and M6's, and can it replace the airbag wheel used on the 88-89 4 point wheel with the airbag?

Just asking, as I prefer the 3 point wheel I have seen in pictures over the 4 point airbag wheel on the 88-89 models.

Finally, is there a "special" M6 wheel in use prior to the 88-89 airbag wheel, which seems to have been used on both 635 and M6 models?

The airbag wheel can be replaced with the non airbag wheels. Obviously you loose the airbag and will need to disable the indicator light. The 3 spoke wheel that you saw on my car was a motorsport wheel and came on the m series as well as many of the e24s with sport interior.

There are also a few versions of the M-Tech 2 wheel:

http://i4.ebayimg.com/07/i/000/bc/ed/cfd2_3.JPG

There is also a 3-spoke with a wood wheel that I like, though I can't convince myself it belongs in my M635 since there is no other wood in the interior. Couldn't find a pic of it though...