I am in the process of a frame-off w/my 65' malibu. Suggestions/opinions on the best underbody/undercoating? Thanks.

Zach,

The best thing to use for coating the underside of your '65 would be POR-15. I have both undercoating and POR-15 on my 4x4 truck that is that is a daily driver in Ohio and has seen 6 winters with salted streets and some of the spots that had undercoating, rusted but the areas with POR-15 held up real good.

I agree POR-15 is the best to use. I used it for my undercoating and love it. It's easy to put on and the results are professional looking.
www.por15.com (http://www.por15.com)
waive

Zach, Am also doing a frame off on my 1965 Malibu. Have replaced the floor pans, sandblasted the underneath and coated with POR-15. It looks great! Just follow the instructions, wear a mask, and latex gloves. This stuff doesn't come off the skin for weeks.

If you want a color-coat, over the POR, it's now possible to use any paint to cover it. POR has just released "Tie-Coat Primer", to bond paint with it's rust-proofing, without getting crinkle-paint effect from the lifting of their product. (I learned the hard way, after spraying $438 worth of catalyzed urethane paint over it. It was an expensive lesson. Guess it happened to a few other folks, as they developed a fix for the problem.)

SS - ouch! I feel your pain.
In certain areas like wheelwells, I like to use the 3M rubberized undercoating over the por, looks good, protects from gravel and is a bit quieter too.