John,
Yes they are really only used for fixed drawbar work like pulling a trailer or manure spreader or the like.They are intended to take the load off the lift arm bushings by transfering the load to the top link pin. They will also keep the drawbar at a fixed height. Do not use them for three point implements.
By the way, you might want to check out the N Board at ytmag.com .
Those guys have helped me out many times on my 2N ( 1947 ) .
By the way , if you are going to do any work with a bushog , get yourself an overrunning clutch ( ORC ) - about $ 50-60 at Tractor Supply . Since your 8N does not have live PTO , if you do not have an ORC , the momentum of the blades on the bushog will shove your tractor forward after you mash in the clutch. You can get a very nasty surprise like that .
Fortyseven2n