Old style lock 2579512 has been replaced with new improved lock 2579771.
Andersen ACTIVE 3- Point Lock Mechanism.
Anderson frenchwood hinged patio door old style multipoint lock.
Deadbolt at handle and locking hooks at top and bottom. 
On the old style lock - both hooks lock in the up direction.
on the new style, Bottom one locks up, Top one down.
Markings on some door locks: US Patent 4 548 432 / 548432

This unit fits The 6-8 or 80 inch tall door.
Overall length: 76-7/16 inches.
Faceplate Width: 7/8 inch.
Backset: 2 inch
Note: Andersen had 3 heights 80, 83, 96 inch tall doors.
Most locks have the 7 digit part number on the face plate

Related Andersen Multi-point locks - FWH68 door
2579771 - 6-8 Active New Style
2579777 - 6-8 Passive New Style
2579512 - 6-8 Active Old Style
2579527 - 6-8 Passive Old Style

Resources:
Article: How to Change Handing of Andersen Multipoint Locks
Manufacturer's Guide: How to Replace an a Multipoint Lock in an Andersen Door

Rehanding an Andersen Multipoint Lock