People on Ebay piss me off
If you wern't worried about numbers matching why bother about putting a fender tag on? much less a build sheet. A wiper motor is differant than showing a car ( with a document) as being something that it is not, even changing from 2-3spd isn't a problem because it isn't altering the cars value in a major way. If you want to alter a car the way you want it's your business, but don't try to "SCREW" others who mabe just getting in to the hobby... that will only ruin it for everyone, after all who wants to continue doing something after they just started and are already feeling like every one is all about making money even at someone elses expense.
Just my two (or maybe three) cents.