2000 Chevy Astro

Safely lift the rear wheel and suport vehicle. Remove the rear wheel. Make sure the park brake is off. On the rear backing plate of the brake assembly, you will see an oval shaped rubber plug. Remove the plug to access the brake adjuster. Loosten the adjuster so the brake shoes close on the inside and the drum will come off. You may have to tap on it a few times to loosten corrosion and dust, but they will come off. When tapping on the drum, make sure to tap in the area if the bearing hub (as seen in the directions).

Here are directions to help. I don't believe you have a floating axle.

https://www.2carpros.com/how_to/rear_brake_shoes.htm

Let me know if this helps.