Gordon:
The Kubota dealer here sell Land Pride. Probably good equipment but twice as expensive as King Kutter. Is it worth the extra money for Land Pride?
Well I own a landpride rearblade series 35, landpride rake and a landpride tiller. All have been tough as nails so far.
I would look close at the quality of welds and thickness of the plates. Thicker plate harder to tear up also more weight the more the better. Another thing make sure it's a fixed rearblade and that the cutting edges are reversable. Just a few things to consider.
Try doing a search on the board for kingcutter boxblade and see what comes up.
Gordon
It is a lively discussion that has lots of info and opinions on boxblades.
I think everyone would agree that you should get a box that covers your rear tracks, which for a 3710 would be at least 66" and probably 72", and that the heavier the box the more effective it will be.
If you are looking for quality and rugged construction, here is a box scraper that fits the bill. I've looked at, and personally used, a number of them through the years...including the Landpride.
I settled for a Gearmore unit. I bought the 2G2 model with the top & tilt hydralics for behind my L35. It weighs 850 lbs so it "cuts in" when you want it. You won't be disappointed.