Hi Dave and welcome to the forum! We have a great, very knowledgeable community here; so you'll likely find the answers that you're looking for from our members. Please let us know if you have any questions or if we can assist with any part needs in the future. Lastly, I'm attaching a link to our site's DIY tech articles from the W123 platform, I hope that you find them useful.

https://www.pelicanparts.com/techarticles/MBZ_Tech_Index-W123.htm