Snapes 73' Dart Resto

Next I think Im gonna try to do is remove all the undercoating on the car, you can see what im talking about in the picture of the a arm and the front door/frame area. it looks like glued on dried mud.
I am gonna try to get one of those needle attachemnts for my air commpressor, see if that works. I just want it all gone, then i'll sand it and seal it it back up.

Any other suggestions?