I've tried to use those backhoe attachments on compact tractors and it's more frustrating than productive. They're too light so it tips easy, have no reach so you have to keep moving the tractor to get a good angle on your work and they're *SLOW* af. As others mentioned, you're way better off just renting a real excavator as needed to dig holes/trenches/footings/etc. If you really do use one that often, buy an older Case backhoe, replace all the hoses on it, change all the fluids and filters. You'll have a legit badass machine that will likely become your most used toy and once you're done it's still worth at least what you paid for it. This old 580 is $8500 on marketplace and it will do a days worth of compact tractor work in minutes:
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