I also have an 843, from the late 80"s maybe early 90's and I purchased the 909 as I was told it would fit, well it doesn't.
The only attachment that fits to the best of my knowledge, with no alterations to attachment or machine is a 911.
If you don't mind cutting and welding you can make the...
Wow!!! looks good kinda, what I was thinking I was going to do, but got lucky and ended up with a 911, could you send pictures of the ball mounts I have not done that yet just wanted to see which holes and or is there a bracket needed?