Is that really a big difference?
I believe the dimples have more to do with the manufacturing process than anything else. I have a whole box of them and have never used the new ones so cant say if there is any difference in action or not. I do know the old ones were made in USA and there there was short time after that when they were made in Mexico. As far as I know you cant tell the difference between those two periods of manufacture unless they are still in the package. The newest ones are made in China and it appears that they do not have the dimples on the bottom as someone mentioned above.
My original question was asked just so I could identify the pre-Rapala from current production models since only one of mine still has the package. Turns out all of mine are pre-Rapala. Best I can tell Rapala took over some time around 2005.