Yup, the 490's were a whole different ballgame...it was something like three way down across the front, three across the middle, then the back corners. 490's seemed to like their fire up front.
In my case, all my student trips were on 490's. When my first pay trip came along, I found myself on the 484, which had a reputation as being a little difficult to fire. The technique I'd learned on the 490's didn't work so well to say the least.
By the time we got from Alamosa to Sublette, Pete Degani had me squared away, and I never had any more trouble. He sure knew the business.
on the other end of the scale, when I pulled my first trip to Silverton on one of the 470's, I hadn't fired one of those before. They have a smaller firebox, but I figured that if I fired it like a 480, I'd be okay
So I had her "stinkin hot & full of water" when we crossed the highway at Hermosa, After the first fire and getting the injector set the steam stayed right on the 200 mark, I knew I was going to make it all right.
The 470's soon became my favorite ones to fire along with the 487, which was always a good steamer.