I hate to break the bad news, but you're missing the entire mounting bracket. Here's a shot of the back side of one:
You're missing everything that's painted green. It normally stays on the blower. You should check with the guy you got the blower from to see if he's still got it. The extra spring is the helper spring, it mounts underneath the tractor. It's only used for manual lift, H models don't need it.
FYI when you get the bracket, you'll need to remove the mower clutch from the tractor (the extra pulleys by the motor). It's held on by several clevis pins, pretty easy to remove. You'll also need to remove the draft plate from the front of the frame - it should stay attached to the mower deck.
Here's a link to a larger version of the photo, so you can see more detail:
http://www.flickr.com/photos/[email protected]/5487342235/sizes/l/in/photostream/