Here is one on-line site for Subaru parts. Do as Subatron mentioned and compare the part numbers between years. But it looks like you got the numbers. Anyway...I have bought parts on-line from the place below. https://www.subarupartsplus.com/
I found it on craigslist but the person is about 1.5 hours drive. Just trying to figure out if it is worth to drive. From a manufacturing perspective, I can see that Subaru would make them the same and just put different part numbers.
Just an FYI if somebody is interested.
Just chatted with a guy from ebay. He has Forester cargo cover for power gate for sale. He has 2015 Forester with power gate and 2018 Outback with a manual. He measured the silver part width and said that the outback version is longer. So I think it wouldn't work. If somebody has both cars would be nice to confirm.