I built one to double-up my mowing width, used a deck off an early 80s sears GT
, was only a 40couple inches...
sure did speed things up a lot!, especially considering I really was mowing a "hay-field" - not a lawn
no matter how much I adjusted that bush-hog, just didn't look quite right!!!
Don't have a pic, long time ago,
my design for the suspension was from a Dynamark I had, so, very similar-looking to Poncho's Ford,
think I only used a 14 hp on it,
just basically copied the tongue design from like the Swisher pull-behind units,
IIRC, I think I ended up using 10" wheels, that way I could raise it enough to mow and leave about 6" of height if needed,
didn't have gator blades then either, would get some terrible wind-rows, so I always used mine to the right side.
deck was pretty heavy duty and stiff to begin with, but, there was still a good amount of flex without the support from the hangers on the tractor to the deck,
a quick, cheap and easy way that I used to "stiffin-up" the deck was I spot-welded every few inches a piece of 1/2" rebar in the "curl" around the bottom lip of the deck,
worked like a charm, glad I used what I did, something smaller would have let it flex to much, and, something bigger would have made it to stiff.
It's kind of neat to take something that really has no further purpose to ourselves, might even be a pita to sell,
and come up with something we would have to spend $$$ to acquire when if we stop and think, we can RE-PURPOSE a couple items we already have, does the job as good or better than we could buy!!!
good luck, know whatever you come up with, it'll be good...