Hi I seem to remember the 886 is a heavy tractor and may be under powered for it"s weight. Don"t know about parts for it. I think the IH rear end might be less complicated than the Deere in some ways, and easier to fix. The Deere is a good tractor if it's not worn out/ been serviced regular. I worked for a guy had them from new in the U.K( same tractor different model number), Got high hours no problem.
He moved to Canada and bought the 2950 I drove used at about 8000 hrs. 10,000 hrs it all started to pile up in the transmission brakes and hyds. It got traded on a 6410.
Make sure all the oil pressure lights work on the dash, If you go look at it, Taking the bulbs out can hide a lot of problems!. The sensors don't flick the warning lights, which can be a tell tale somethings up, you need to know what your looking at when buying these tractors.
That back end is totally relying on oil pressure, if it's getting worn oil doesn"t go where it should, Hi lo clutchless shift, steering, brakes and front hyd pump start to do stupid things or wear due to low pressure lubrication in the system. Parts may be a stupid price they are here in Canada through Deere. I got an 1830 here in the shop, that is a very similar rear end. There are a lot of $2000 parts in that, and a big pile of O rings that could be leaking. I'm not sure I can fix it/ find out the whole issues with whats wrong. looks like it has major wear issues in more than one place, leading to multiple hydraulic circuit failures. My thoughts would be buy the Deere if it's low hours, well maintained. IF NOT RUN HARD AND FAST THE OTHER WAY! Yes Capital letters means I'M yelling it L.O.L. From what I see with this very genuine well serviced/ looked after one owner 1830. It has 17,000 hours and could be ready for the north 40. You don't want a huge pile of trouble like this is.
The problems started real sudden with it while brush cutting, If my customer told me everything to the best of his ability!. The 2950 was more of a gradual decline, the high low started downshifting on it's own, when the motor revs dropped off, and the steering and front pump played up too.
Just my thoughts from my experience with these 2 Deeres and I'm sure truth be told they aren't the only ones like this around. Good luck with your choice. Regards Robert