That could be the upgrade kit. Have you looked at the Bachmann website to see if that is what it takes? Then order one from an online vendor like www.trainworld.com because you can save at least 20%(maybe up to 50%) of what WBB(Williams by Bachmann) wants for the item.
I have upgraded a couple of F-7's to power and found that the mounting bracket (for steps)near the motor needs to have it's hole drill out by just a little about one sixty fourth or one thirty second over size. Don't drill too large or the screw head won't let the mounting plate stay attached, in other words if too large a hole the mounting plate falls off. Also you will need to swap over the couplers from the unpowered engine to the powered unit. Second thing, if using with another powered unit be sure they both run at about the same speed around the track, put both on track at the same time and run them separate from each other(uncoupled) and see what happens. If both don't run about the same speed one may burn out the others motors in long term usage.
Lee Fritz