As far as I know all Ford E 350 and 450 and up have rear parking brakes, they have a disk and a drum all in one with the parking brake actuating the the shoes.
I believe the the Chevrolet or Work Horse have the drive shaft parking brake.
They are scary, if a "U-joint" brakes completely there is no parking brake at all.
I have a 2001 Ford E 350 V-10 with front and rear disk brakes and rear shoes for the parking brake, that in an emergency I can use to stop the RV.
I have the overdrive rather than the towing, the v-10 engine has more power than what I need to pull the toad.
navegator