a rear 3pt grading blade / plow blade for snow. can have some descent weight. problem with them is, normally no easy quick way to add extra weight to them.
most box blades, either already come with some type of holder on top for more weight. or for cheap and fairly quick mod can normally accept a varity of different weights, (concrete blocks, concrete bags or sand bags, large rocks, large part of a tree trunk toss across and chained / strapped down, etc...)
bush hogs with others, just hang way to far out the back of tractor. and just a simple turn can easily take a good amount of extra time double checking you do not hit anything.
on other hand, i gotta love a backhoe. they add lots of extra weight, and if i am moving dirt long distances, and do not have a dump trailer handy. for me the 555c i will load up the FEL with dirt then, i just pull a lever turn seat in the cab drop out riggers take a swipe at dirt load backhoe bucket up. put it in transport position. and pulling out riggers up while turning back around and ready to change gears and move on out. for me the extra dirt in the backhoe is about 1/4th of what is already in the FEL bucket. so instead of taking 5 trips i can do things with 4 trips. and when it takes me 10 to 15 minutes per trip. that backhoe quickly makes up for itself both in time and on gas. that and backhoe bucket can make for a nice "compaction" in spots were you can not easily drive over.
i am not very thrilled about having a 3pt finishing mower on. the decks on them tend to be thinner metal and much easier to bend. and some times i can get myself into tight spaces and easily nock into say a dirt pile or edge of dirt and could quickly destroy a 3pt finishing mower. then again this is me. when doing FEL work i can be rather aggressive and use every bit of HP the tractor has and running in higher gears. along with i have a varitiy of different slop hills. and from time to time i catch myself not paying enough attention. and can have FEL all the way down. and bucket curled just right. to bust a 3pt rear finishing mower off the 3pt hitch assembly. poor backhoe sub frame has found out a couple times *frowns some* it is by no mean intentional. just get in a hurry. and want to be done. and actually have enough time to eat and shower before hitting the bed. let alone time to relax a little before head hits pillow.
when using FEL, even with a belly finishing mower, i will take off before using FEL. to many times i could easily get hung up on a belly finishing mower or destroy the mower.
a 3pt weight box /
ballast box is nice. and if all i did was loader work say at some commercial nusery or sand / rock gravel pit. ballast box would most likely be the best. ((less stuff hanging out rear of tractor)) but for me majority of the time, it is driveways, dirt roads, paths through woods leaving out and re landscaping a spot for better mowing. and having backhoe or a box blade, would come in extra handy. and allow quicker work.
3pt carry all. can be nice as well. but generally if you are doing FEL work. you do not have a lot of use for the 3pt carry all at the same time. it just doesn't do any ground engagement.
3pt plow, can add some good weight, but like bush hog stick to far out the back.
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to above box blade or a backhoe. for FEL work. and if possible fluid filled rear tires. for extra weight.
i honestly do not do enough stuff that requires rear tire rim weights. or like weights. and would more likely spend cash towards chains for rear tires. than go for rear wheel rim weights.