Before (#3), you were in the Lake Whatcom drainage area, but on the other side of the bushwhack, you are now in the Lake Samish drainage area. This cache is placed at an important junction, right next to where the beginning of Silver Creek (the one with the waterfall) crosses the road. The right fork goes to the top of Galbraith Mtn, and the Left fork goes to the summit of Lookout.
Not to be confused with a nearby trail with the same name, the Lookout Loop Caches are part of a mini-series I've placed to highlight a fun loop you can do that takes you to the north summit of Lookout Mtn. While the loop itself is only 9mi, you will end up going about 12mi RT including the trip from the trailhead to (#1). You can also park at (N 48° 43.152 W 122° 21.320), which will cut your distance down to 10.5mi RT.
Remember to check each cache logsheet in the series for part of the code that will help you get to The Final!
The cache can be reached by following the loop to (#3), and proceeding left (downhill) for about 2/3 mile until you reach this split. Yes, you are going the right way, and unfortunately you will lose 350' of your hard-earned elevation. After getting the cache, turn left and proceed upwards to (#4#).
Have Fun, and Happy Hunting!