As we discussed on the phone, someone has modified your door jamb. You now have a striker plate, instead of a striker pocket.
The customer service girl you talked with has been corrected. She was in error as to the correct part that you needed.
The more important thing is that according to you, the door jamb has been butchered and probably the correct stainless steel striker pocket will no longer fit correctly, along with it's brass shim.
The 72 and up striker pockets and brass shims are available, separately.
Probably all you can do is plate the door jamb, and start over, if there is enough clearance between the door and jamb.