The peel/seal product is intended for aplication to sheet metal duct work in HVAC ( heat/cool) applications and there is no reason it can't be used on or in our old trucks. It is meant to take out the sound of ducting when the blower fan comes on and is used a lot on open roof tops where the AC units are placed. It costs less since it is made in mega quantities. The dynamat is a different polymer which indeed has a sound/vibration attenuation quality and is made in lesser quantities so costs more. It is overkill for most trucks anyway. I say peel and stick away. I have used both. Jon
