As a general rule (ideally at least), you would like all your rear implements to be as wide as your rear tires PLUS a bit to make sure tracks are covered while driving straight or turning with the implement engaged. You can add a foot or so to a landscape rake because it doesn't deeply engage the ground.
Does the "38" in
L3830 mean 38hp (or thereabouts)? If your rear tires measure to a 73" track, your tractor should have enough weight and power for implements sized using the guideline above and refered to by John Mc. For an example, my 24hp tractor has a rear track of 52" and came dealer equipped with a 66" boxblade. I asked about dropping down to a 60". They said I'd be happier with the extra width. I've never tried a 60", so can't say if I'm happier, but 66" seems to work fine.
Any implement, be it rear mower, brush hog, or box blade that is as wide or wider than the track of your rear tires will allow you to get close to a wall or whatever and still get the job done. The width of the tractor won't interfere with the action of the implement. Whether it is by design or by happenstance, tractors usually work fine with implements slightly wider than they are, but it depends on your needs, too.
Disclaimer: I am not familiar with your particular tractor. There are exceptions to "general" guidelines. As JMIII suggests, an aggressive application may require a narrower implement.
OkieG
