x2 on probably being your wheel cylinder. Ever have your BRAKE light or ABS light go on in the cab possibly after a hard stop? Or your BRAKE light mainly staying on (Low fluid). That a long with dropping fluid levels and difficulty stopping quick was what I noticed when my drivers side and passenger side wheel cylinder went out.
When you replace the wheel cylinder on one side I would highly suggest doing the other. When one goes its only a matter of time before the other does as well. Additionally you may want to replace all the little springs on your drums because I would bet that the side that is leaking is caked in fluid.
'99 Ranger XLT
3.0L Flex Fuel 2wd
Stock Ranger on Kelly Safari tires on stock wheels.
7.5 3.73's w/ L/S
3" Summit Body Lift
3" Spindle Lift
2" Rear Blocks
33" Mastercraft Courser CT's fitted on 17" IONS
8.8 4.56's w/ L/S
Coming soon: Exhaust