Other than measuring it, any Auto Parts store has this information. The maximum wear diameter of the drum is cast onto the outside of the drum.
You can find the '94 Dodge rear drum brake diagram online at places like Dodge Ram and the Dodge Forum. You can also find them on YouTube.
Master cylinder or drum brake (hydraulic slave) wheel cylinder or disc brake caliper cylinder? drum brake shoes rear
In the Haynes workshop manual.
should just pull off if parking brake not engaged
Most auto-parts stores that sell brake drum assemblies will also provide you with an assembly picture. The brake drum assembly pictures can also be found at most local libraries.
The wheel cylinder has failed and will need replaced.
Front disc/rear drum
With a big hammer. hit it on the edge
Disc/drum brakes DOT 3
Brake drums can be resurfaced by turning the brake drum in a brake drum lathe. When the brake drum has deep grooves in it, it cannot be repaired.
remove wheels, release emergency brake and drums will come off.
drum brakes on rear of 1996 ford not disk