Greetings and welcome to the vintage Airstream hobby. A 68 Overlander 26' storage unit. Nice. Some of us say the 68 is one of the best vintage Airstreams, and I'm one of them.
I believe you will find vintage Airstream experienced folks here more that willing to share their knowledge and experiences in an effort to help you with your project. We all were new at one time. There are no "dumb" questions as they say.
I renovated a 66 Trade Wind 24' which was one model size smaller than your 68 but very similar. See photo. I also did extensive work to my son's 69 Globetrotter 21' (first year of the new body style) and now I have a 75 Overlander 27' which is a lot different than your 68. I renovated the 75 also. Mark me as down as stupid crazy, or stupid and crazy.
Maybe you would like to start a project thread in the Airstream Trailer Forums found near the bottom of the Forums page. There is where people interested 68 Overlanders tend to lurk, find interest, and help each other out with their build projects. We usually don't post in individual categories like axles, or frames, or plumbing. Everything Overlander is discussed in these more "general" threads. Here is a link to the mid sixties Overlanders. Stay up all night and read some threads. You will learn a lot about your rolling "storage unit". I like Joyflea's 67 Overlander "Big Fix" thread. This man can build anything.