Well, well, well,
So the 2002 E350 cutaway has rear drum brakes. As j-d mentioned, I do strongly recommend adjusting the brake shoes for best braking performance as well as best parking brake performance.
Just about every vehicle with rear drum brakes are adjusted without disassembling anything. Leave the wheels on the vehicle. Just raise the rear of the vehicle, placing the rear axle on very strong jack stands, positioning the stands as close to the leaf spring attachment points as possible. Identify the 1.25" long oval rubber boot on the back side of the drum plate. Remove the boot and adjust the brake shoe star wheel inside.
For my previous Toyota-based motor home with rear drum brakes, after getting a new rear axle with new brakes from a recall, I had to adjust them 18 to 20 times per side until the shoes lightly contacted the drums after pumping the brakes. Between each adjustment I pumped the brake pedal to re-center the shoes to the drums. If there was no contact after pumping the brake, I did it again. When I was done, the rear brakes came to life.
If your rear drum brakes are severely out of adjustment, they are likely doing very little to nothing. In my case, until the rear brake shoe adjustment, the front brakes were doing all the work. After the 18-20 cycle adjustment process of my rear brake shoes, my motor home braked so much better with greatly reduced stopping distances. Driving in mountains and canyons went from terrorizing to secure driving. Needless to say, the company that performed the recall failed to adjust the rear drum brakes before sending me off.
Oh yes, the parking brake came to life as well.