A new garage door install isn't a weekend project most homeowners should take on alone, and that's true whether the house is new or, like a lot of Lynnville's stock, going on ninety years old. The door panel itself isn't the hard part - it's setting tension on a torsion spring under load, squaring a track to an opening that may not be square itself, and getting the header anchor into solid framing instead of old, dried-out wood that looks solid but isn't.
If your garage was built close to that 1938 median, there's a decent chance the header has been patched or shimmed at some point by whoever did the last repair, and you won't know that until the old door comes off. That's not a DIY red flag so much as a reason to have someone on site who can stop and reassess instead of forcing the new door onto framing that needs attention first. We'll say plainly: if your opening is standard and square, a capable DIYer can handle a basic swap. If it's not, the spring and the header are where people get hurt or end up redoing the job twice.