I read this post and many others looking for the easiest way to remove undercoating before I started my undercoat removal project. I figured I would update everybody now that I'm almost done with this little slice of heaven project. What worked for me was a combination of solvent, heat gun, rigid scrapers, flexible scrapers, 3M abrasive disks, wire brush, dynamite and weapons of mass destruction. In other words, there is no magic solution! It seems like each area required its own particular method to get the stuff off. I also think Datsun management must have been paying bonuses to whoever could put the most undercoating on a car the day mine was built. Anyway, my point is to just get in there and do it. Once you finally get started it becomes a kind of twisted quest to get all the gunk off your car. At the time of this reply I am welding in the sub-frame connectors and feeling a great weight has been lifted from my shoulders.