I have a 6610 and just got a Bush Hog 2426QT FEL new with a bale spear and heavy duty bucket for $5,300. That's a point of reference. My papaw has a 3910, so I'm very familiar with them, around 42 HP if I remember. Bush Hog will certainly make mounts for your tractor:
Bush Hog ® Agricultural Products
Go to the Ag Loader link, look for the front push models. You might be able to go with a "compact" tractor version 2346QT (25-50 HP tractors), or the 2426QT (35-75 HP) like mine. The color will match, and it is made really well for the money. I looked at Woods, Quicke, and a couple others, for the money, the BH seemed like the best option. It has a quick attach bucket, so you can switch it out easily with the bale spear, or just drop it if you don't want the weight or obstruction out there. The whole thing will also quick disconnect from your tractor. Check out the vids on the BH web site. I will probably never do that, but I CAN!
Here's what it looks like installed:
Good luck, and enjoy! (By the way, check into getting a tooth bar! Mine's ordered but a little late getting here.)