l have the replacement flasher but dont know were the orginal is at.

Which car?

They get placed in all kinds of different places in different cars.

Check in the fuse box which in some ford vehicles is under the hood beside the battery. Sometimes its in the vicinity of the driver is knees.

Sometimes its back near the firewall above the gas pedal.

There is more places they hide it...

go inside ur car, close the window & doors, make sure no noise will come in once ur inside. turn the ignition key to ON position but do not start, switch hazard on & listen carefully if u hear ticking sound, locate where it is located. if u do not hear any sound, turn off the hazard switch, then now try the left turn or right turn switch, if u still can not hear any sound ticking (which is supposed to be the flasher relay) the flasher is dead. Now since it does not make any sound because it is dead.. the only way u can find where exactly it is, is to use the manufacturers repair manual on electrical circuit & component location. Or if u have money at least less than $20 u can access the whole thing about ur car is repair manual online by subscribing to a repair reference subscriber like the Alldata or the Michell on Demand.. Or u can go to ur car is dealer & ask for one. (not free ofcourse) . But generally they can be found underneath ur dashboard & sometimes it is inside the steering wheel /column.