What is "correct" for undercar undercoating?

I have a 72 duster and mine was undercoated from the factory (rock solid underneath) and the factory stuff is very thick and unattractive looking lol....and kind of spotty....I am sure it came down the line and go a couple pass's of the gone and was on its way.

I am undercoating mine with rubberised spray can undercoat....I think its made by dupli color.

The stuff takes a few days to fully dry but when it does it has a nice rubbery coating and it lays on evenly and smooth and really shows off the shape of your under body metal because it flows with the contours well.... I would say it sprays on at about a 32nd of an ".....thats just with a coverage coat...you could build it up more with a few more passes.

I would say about 4 or 5 cans would completely coat the underside and at a cost of about $6.00 per can.

My paint store sells some even nicer stuff (not sure of brand name) but its $16.00 a can