I bet that cooling assembly is a snug fit.
Hopefully no need to modify the bucket 
I had to check!
Stopped the ongoing movie, told wife I have to check something in the garage 5 minutes. Not first time.
I do not like to think about fit or not when I can verify it direct.
I made the bulb taller, 13mm more inside bucket.
It fits.
Need to fix wires inside bucket with tape.
It looks like a refugee camp for wires and thicker connectors!!
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I closed it and fastened with the 3 M5 screws.
All functions are functional too.
That LED H4 fan has worked fine since 2015.
I had another one in my K2 where the fan started to scream after a season.
This yellow/white spec 3800 and 4000lm eBay vs Amazon descriptons.