@Jeff T posted:Are you sure about that?? The upgrade is buying a loco with a larger motor as the smaller ones can't be swapped...
I'm sorry if I'm mis-remembering. I don't want to spread misinformation. If it's not the Polar Express Berkshire Jr., then I must be thinking of the Hogwarts loco (4-6-0) that started out with a small motor and later Lionel installed a bigger one.
I know that Forumites have inquired about upgrades, and I thought some folks upgraded one of them. And yes, given a choice it would be better to buy one of the later ones factory-equipped with the larger motor.