Around what year would you say Castellano had become truly unpopular? I mean he lasted as Boss for almost 8 years...When did the cracks in his power and respect begin to show?

Slowly from 1981,when he ordered the murder of Conneticat based Gambino capo,Frank Piccolo.

He was always unpopular but nobody could do a damn thing about it. 1983-84 was when the tide started to turn. The govt was after him, roy demeo was gone,nino gaggi was going to jail. So for the first time he was very vulnerable

He wasn't always unpopular, at least not outside of the Manhattan faction. He had pretty much supreme allegiance amongst his crews that made up his faction. Guys complained about money but it was never any plotting to kill him. On the other hand, pretty much from the moment he was made boss, he was despised by the Manhattan/Dellacroce faction, for obvious reasons.

However, once Gotti became boss, he received the same complaints, about being cheap, and demanding too much of a percentage of the money that was earned by his men.

well actually it'd be every increase of percentage he took from his crime family. also working really close with the genovese crime family i'm sure that also made him that much more hated. there is no key time in which he become the most unpopular. BUT i'd say in my opinion it was either when he didn't show up to neil's wake or when he caught the court case and everyone thought he'd roll.

That's it basically it in a nutshell.