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When you tow with the tractor, DON'T use the 3pt. Use the draw bar. That's what it's for.
Work out the physics of the mounts. The draw bar is mounted below the rear axle. Adding weight there is less likely to raise the front end up and flip the tractor over on top of you. The 3pt lift arms (the ones with the power) mount above the rear axle and will quickly make the tractor prone to flipping.
Oh, if you do use the 3pt, make sure to use one of the deals (like sold via this site) that encorporate the top link. If you don't, when you stop, the 3pt arms are not constrained from raising as the trailer plows into you. At some angle and force, the coupler will pop off of the ball. You really don't want all that weight in the seat with you!
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