170, 198, 225 how many of each?

I always thought it was odd that they dropped 170 and replaced it with a 198. I see the reason for the 170 in the early 60's to compete for sales against the Corvair,Falcon etc as they were of about the same displacement. But a 198 ? Could it be it was insurance related ? I know that Ma Mopar started installing 3 speed trannys in the high performance cars to get around the higher insurance of a 4 speed car.I had a 198 in a 71 Duster,always thought it was a 225 till I removed it and installed a 340. Ma Mopar has thrown curve balls to get around pollution controls and fuel economy mandates. Like when the PT Cruiser came out and it is listed as a truck. I have a 07 PT, the registration and title says TRUCK.Somebody out there must know. It sure ain't me.....