For how old this thread is, I'm sad to say it is still relevant. I just replaced the LMC sending unit in my 72 c10 that's was in there for about 5 years. The float worked fine on that one. It was the pivot rivet for the float arm that went bad. So I ordered one from Brothers trucks on 9/1/18. Received it, installed it, worked for about a week. Verified everything else was good leaving only the float as the suspected failure. Emailed brothers and they overnighted a new float to me. Just got it today and am looking at doing this job again.
I wish I had followed my gut and kept the float off my LMC unit before tossing it. Oh well, live and learn. I'm gonna test this one before it goes in first though. Putting it in some boiling water should suffice no??