MFWD / 4x4
PROS...
--going into a turn... you keep turning vs front wheels acting like skies and just keep going straight.
--getting you through a "wet patch" if just 2WD, you hit wet patch you are stuck. hopefully with 4WD you can maintain enough traction to keep going.
--more likely keep you going straight... how many times have you had a rear blade, or something else behind tractor and pulling it. and one side gets loaded down... to point it starts pulling the front end around on you? and you are having to turn the front wheels (on 2WD) tractor or perhaps tap split brakes (rear left/right brakes) to keep going straight? MFWD / 4x4 should keep you going.
CONS...
--you may need to change front tires and rear tires at same time. due to "ratio" issues of tires being within a certain tolerance. if tolerance gets out of whack you are at higher risk of doing damage to the drive train / system of the MFWD / 4x4 function of tractor.
--costs more up front
--cost more long haul (maintenance side of things)
--you need to remember to take MFWD / 4x4 out of gear. on pavement / concrete / hard surfaces. or you can damage the drive train as well as tire treads wear quicker when in MFWD / 4x4 and on hard surfaces.
MISC....
MFWD / 4x4 tractors might be ballasted / weighted differently. in order to take advantage of MFWD / 4x4 function of tractor when pulling stuff.
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keep in mind what is more important to you.... field work = money making? duals on older 2WD tractor for flotation / less compaction. and larger machine might serve you better?
or is just a general multi purpose machine what you need? more like smaller machine with MFWD option and some additional smaller addon's to make life easier and simplier for you.
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goto the various tractor manufacture websites out there and go through there "build a tractor / configure a tractor / what ever they call it" and familiarize yourself with the "additional options" for different make/model of tractors even from same/different manufactures.
www.tractorhouse.com = while a lot of used tractors show up in lists, there are some new tractors as well. more of goal to use as a "research tool" / doing your home work of see what is out there.
SearchTempest: Search all of Craigslist nationwide & more = search multi cities of craigslist .org at one time. some additional things locally normally show up.
Tractor Attachments And Skid Steer Attachments For Any Tractor Or Skid Steer = just "attachments" for tractors. last time i looked they did not hit heavy in larger farming operation equipment. they do have a lot of various equipment. (good starting place to see what is out there) lots of videos / details of what things do / how to use them.
goto a few local dealers in your area. and set in different size machines and test drive each one. for say 15 minutes. if they have something you can hook up to it. or perhaps a FEL you could use to push some dirt around. might be advised. there can be a large difference in how things are laid out as far as controls on tractor. and overall power factor / feel to things.
--most tractor manufacture websites have some sort of "dealer locator" enter zip code and find. (starting point)
--look up in old phone book for "heavy equipment" to "tractors" to "farm equipment" there might be some local mom / pop shops around. that may not show up.