At the dinner table Jamie mentions that the Chevelle was an SS-396, but in an earlier show he tells someone it is a Chevelle SS-454. But he goes on to say the SS-396, which was Joe's, was totaled. The SS-454 is the car he and Frank restored.
When Henry talks about Erin's speeding, he says it was in Joe's "hot rod". The Chevelle was considered a "muscle car," not a "hot rod." But Henry grew up in the era of the hot rod so that's his frame of reference. He'd call any souped-up car a hot rod.