Brake drums are pretty easy to change but sometimes they may be hard to get off and may require the use of a brake drum puller.
However most brake drums just slide off the brake shoes and then you need to make sure the brake shoes are adjusted to fit the new brake drums.
It's also a good idea to replace the brake shoes if needed when replacing the brake drums as well.
Brake drums usually last 100,000 to 180,000 miles and in some cases brake drums may last as long as 250,000 to 300,000 miles.
The brake drum is a very durable piece of the brake system in a vehicle and although the brake drums can wear down some and develop cracks the brake drums typically last for a long time.
The brake shoes will wear down much faster and the more you use the brakes the faster the brake shoes will wear out as they press against the brake drums to stop the vehicle.
Brake shoes typically last 30,000 miles to 50,000 miles and if it's been more than 20,000 miles since you checked your brake pads or brake shoes it would be a good idea to inspect the brake shoes and brake pads for wear.
If the brake pads or brake shoes are getting worn down then it's best to replace them especially if you're venturing out on a long road trip.
Inspect the brake rotors and brake drums for groves and cracks and if they have groves or cracks in them then they need to be replaced.
Or if they are getting thin the brake rotors or brake drums need replaced.