Chevrolet Repair: Rear Axle Assembly, chevy astro van, rear axle assembly

Question
Hi, my mechanic said I need to change my entire rear axle assembly. This is for a 1995 Chevy Astro Van 2WD. At first we thought it the wheel bearing, but when he open up the wheel and the drum of the rear axle. The car is in park, but the rear axle you can turn it while the brake is in park. He said there is something wrong so it need to be change. You can turn the rear axle and the driveshaft doesn't move at all. So he said change the entire assembly? If there something wrong, or it is the brake?  

Answer
Hello Duong,
I would at least want to remove the cover, and look inside.
A broken axle shaft can be replaced without replacing much else, and usually without dissassembling much.
But if the differential gears inside the rear end are broken off, it will be easy to see.
Even then, it can be repaired, but a broken pinion shaft or carrier assembly requires much more work, and may be easier to get a used one and swap.

Van