HO52 rear end education

[66 lwb cs]

OK I did the search thing and I know that somewhere I saw some stuff about the HO52 rear end being a bad rear end to use but I can't find out why I even did a search on google and some liked the rear end so if someone could point me to the link or educate me on what's bad about the rear end. I think I understand that most had steep gears so is it not possible to change to a less steep gear in them also can they be switched over to 5 lug and can they accept a disc brake conversion? Any answers and education would be appreciated. Sorry if this was covered somewhere but I couldn't find it so don't beat me up too bad thanks. Also the truck I am buying the owner says it has the Heavy duty rear end in it complete with overload springs what rear end would that be a Dana or the HO52? He is my father in law and the origianl owner but just knows it's the heavy duty rear. It is a 3/4 ton camper special long bed if that helps with the 327/TH400. Thanks in advance.