I was re-watching season 6A recently and came upon a certain scene in Cold Stones. Before Silvio and Carlo kill Fat Dom, Silvio makes a remark about certain droppings.

"We need an exterminator, these are rat turds."

Also the name of Carlo. We all know in The Godafther that Carlo Rizzi was helping Barzini. Seems to make sense that Carlo would be the one to flip.

to be honest i would have never have seen that coming theres no way i would have made the connection

The only clues I saw was how Carlo was missing or late in the final episodes and he acted a little bit differently

It's not really that far-fetched. Chase did portend an awful lot, almost as much as he used symoblism.

Speaking of rats, was Jimmy actually a rat or was just Tony's assumption?

He did get bail awful quick, for an alleged capo in a heroin case, but I don't recall if they actually ever verified him being a stoolie. I'll have to check the season one dvd.

He was a rat, guaranteed.

Trying to get people to talk about the Filone hit, etc.

I was never convinced that Jimmy Altieri was a rat. I think he was in the wrong place at the wrong time (when the paranoia about having a rat in the Family came to surface). IMO it was Big Pussy all along, and Jimmy took the heat (or more properly, the bullet) for him.

And that's why its (or rather, it was) the best freakin show on TV.

Yeah, I have to agree with this.

Re-watch season 1 again, it's VERY obvious that he is a rat.

I agree. His reaction to Silvio calling him a rat and pulling a gun on him indicates that he is, indeed, a rat.