Lets put it this way... I've completely removed seam-sealer from three different cars now... a 71 Fury III, a 70 Barracuda, and a 70 Challenger. And coming up very quick here, my 74 Challenger. I weigh everything. The least gooped up ov the cars was still 10lbs worth. The Fury more like 15. Thats just the seam seal. I got lucky with the last Challenger... NO undercoat at all, but i've never bothered to scrape a car yet. I've heard anywhere from 30-60lbs. Its worth the grief.

I've read about all the different methods, and honestly, i think just taking the old chisel to it dry is likely the best bet. Maybe a wire wheel. No way i'm liquifying that sh!t and going that route. My 72 Charger must have had 1-2lbs worth ov undercoat on the inside ov the trunk... on the quarter. Useless. I swear... they got paid by the gallon...