Here are some pics, i think it goes in that space shaped like this () next to where the filter goes...
It goes under the tab on the filter. You are lucky you didn't lose it. They sometimes shoot across the room, or just fall into the pan and never get found again.
I am pretty sure that the plunger goes in first, with the thin point in the tip of the spring, then the spring against the tab on the filter. Sorry it took so long...
I lost that little piece that looks like an icecream cone up in the transmission where you told me to put the spring.... any ideas on how to get it out?
No, it doesn't go under the filter, per se, but the filter has a half-moon shaped tab that sticks out and presses that spring into the hole. The tab is part of the sheet metal that sticks outside of the bolt pattern.