I looked pretty extensively and even called a few places, but I couldn't even find a used subframe for this series of tractor for sale! Even in salvage yards.. They mainly deal with compacts and larger tractors though.. In fact, one of the guys I talked to said with a narcissistic tone, "Nah, I wouldn't have anything for that size tractor!".
There is almost zero chance anyone is going to have something like that for sale. These aren't like cars where there are thousands of most models sold for salvage each year. If a unit is usable, there is plenty of profit in repairing it and selling it complete, rather than parting it out, and waiting for their money.
What there are lots of, is used units for sale with the factory backhoe on them. And, if that doesn't suit you, really good deals to be made right now on new ones.
Before you get too deep into this, you should consider what it is going to cost to get all the materials, and how much time is going to go into it doing all this. You would very likely be way ahead, to trade it for a 2310, or other tractor that is ready to go. Just the time you will spend alone, is probably worth far more than the cost difference.
It would seem crazy, but if you really want your tractor with a backhoe, buy a 2310, take all the backhoe parts off it, and put them on your 2300. Then, sell the 2310 you bought as a 2300. Bet that would cost you far less money, and small fraction of the time.
It's certainly going to be better to have it all factory installed, if the day comes that you, (or your heirs), ever want to sell it to recover some of your investment.
I'm all for fabricating stuff. But this project seems like a bad idea.
