Are you looking just to replace the bulbs, or the whole lamp assembly?
I'm asking since my understanding is LED's require a different reflector then an OEM light...
A reflector designed for incandescent bulbs (btw, halogen bulbs are incandescent) is designed with the light coming from a very small location (where the filament is). HID bulbs emit from an area which even in the same bulb size is typically a longer line, and LEDs bulbs often emit from multiple ... LEDs... at the same time, in an area which is much larger than the light emission area of an incandescent.
As such, HIDs and LEDs
in OEM configurations (ie, as installed in a car from the factory) typically shine through a lens - "projector" style - so that the light all goes where they want it. When you put one of these bulbs in a reflector that's designed for an incandescent bulb, because the light is coming from more area than the reflector was designed for, you typically get a wider "spray" of light.
This may be mitigated by whatever lens is in front of the reflector - on my motorcycle, the spray definitely goes wider left/right, but there's still a sharp cut-off above (where it would interfere with oncoming traffic) because of the design of the lens (lucky me; also this is with an HID which has a different pattern than LEDs).
This spray can matter significantly on the road because that extra light goes into oncoming drivers' eyes.
This spray is likely to be beneficial to a tractor driver, because they're not dealing with oncoming traffic, and it in effect makes the light somewhat more "flood" than before, and since the LEDs are so much brighter than the incandescent, it's actually an overall win.
The only concerns I have as a tractor owner about using LEDs are
1, will the LEDs survive in the tractor (cooling & dirt/chaff issues)
2, will my eyes survive the reflected glare when my bucket is in front of the headlamps