I bought a quart of this stuff for $11 from NAPA called "Restore" rust converter and protective coating. I brushed it on the center-section of my rear 9" axle housing. Looks great!!!

Before:
http://www.superford.org/getfile.php?id=42506&toggle=fullsize&filename=rear9.jpg

After one hour:
http://www.superford.org/getfile.php?id=78201&toggle=fullsize&filename=restore1.jpg

wow that looks great

Here's another shot after finishing the whole rear axle:http://www.superford.org/getfile.php?id=80241&toggle=fullsize&filename=restore3.jpg

looks like the thrid can use another coat

Looks that way, but I just put the stuff on the 3rd member a few minutes before taking the pic. It's totally black after 1-2 days. The hard part was cleaning and scraping off 20 year's worth of grime for the prep work. I think I could do the whole undercarriage with just a quart. Something to do this Winter!

So is this stuff like POR 15? Do you know how durable this stuff is?

Looks good!!!!!!!!!!!!!!!!!!!!

I used the same stuff on the body rust all over my '90. It converted the tailgate rust to a black primery stuff, strong enough to stick on some body trim to cover the holes.

It's good stuff. I'll be putting it all over, once I get this thing MD inspected.