If the 126s are like the 123s, it’s likely you just have peeling polyurethane but the wood itself is fine. I removed all the wood pieces from my 82 300D and took it to a local antique refinisher. (It took some effort to find someone willing to take on those thin veneers.) He used a chemical stripper to take the old polyurethane off and then sprayed on several coats of new poly. I opted not to stain the wood as the natural color was very nice. Apparently the original wood wasn’t stained, either, but the poly darkens considerably over the years. It’d probably be very difficult to match the existing color and finish, but if you’re looking to re-do all the wood, it’s a great result.

Here’s a good DIY-write-up if you want to take it on:

http://boostnbenz.1baddsm.com/DIY/Wood/

__________________
05 E320 CDI - 185K miles
82 300D - 200K miles (sold)