Well, it happened to me
 

While doing some cleaning and maintenance on my 1872, I discovered all four of the bolts from the frame to the differential had broken. I took things apart enough to get at them, drilled and used an easy out, the first one came out (tough, but it did come out). None of the others will come out, I rounded the shaft of one easy out and broke the handle, bought a better handle and snapped the end off of two more. Figured I would take it to a machine shop and started taking it apart, when I found that one of the cone bearings was damaged (one of the rollers was chewed up and actually fell out of the race). Now I find this part is NLA, any one know where I can get it? I searched for cub cadet 741-0369 and every site that comes up says to call them, Calling has turned up nothing so far.

It's just a bearing, pull if off, it should have the bearing number on it and you should be able to get one from a bearing shop. Easiest way to get the broken bolts out is to weld a washer to the bolt and then weld a nut to the washer. They are Loc-Tited from the factory so they are a PITA to get out, ask me how I know.

Had the same issue with my 1450 years ago. I ended up removing the axle tubes on each side, which exposed the broken bolts. I took a "vise grip" pliers, and removed all the broken bolts. It was a good time to look at axle bearings and seals then.

Would have if I could have, but they broke off flush to the case.
I already ordered the axle bearings and seals when I started this, as I am one to "you might as well while it's apart" I would never have something this far apart and not replace something bound to go bad later. As it happens, one axle was kind of sloppy in the bearing, so, good thing I did. This was all before I found the bad cone bearing. The machine shop I was going to take it to sells bearings (its where I got the bearing for the front pto a couple of years ago), I figured on asking them, but wanted to ask here to cover all bases.

Actually, Sam Mac, I just re-read your post, I didn't think about a washer first, my son has a mig, I might think about that. Yes, I noticed the loc-tite, which made me question all the posts I've read about these bolts working loose and then breaking, as tight as they are, there's no way they worked loose first. As a matter of fact, when I first got this tractor, I questioned how good an idea it was to have only four bolts (yeah, I know, there's another bracket on the hydro) and thought I would make up a plate that utilizes all of the bolts in the carrier, guess I should have at that point.

Find some washers that fit close to the broken bolts, weld them to the bolts then weld a nut to the washer. The heat from welding will loosen the Loc-Tite and you'll be able to back them out. The washers protect the aluminum case but you still need to be careful. I've done a few this way and it worked well for me.

If there flush, you might be able to put a chisel on the bolt, and hammer it out enough that you can grab it with channel locks.

If there is no loctite..... maybe.

All of the bolts have been drilled to accept an easy out.

try a little heat to soften up the locktite that might help but be cautious as its aluminum. heat will help thats why the welding washers and nuts works... this is how i look at it rite now part is useless you cant make it more useless rite? and also it is replaceable so worst case you find another one