I remember seeing some header gaskets that were pricey but leak proof mention on the site. I’ve got a stock manifold that I cannot get to seal. Any body help me out with what they use?

Remflex

^^^^^This^^^^^

Either the exhaust manifold is warped or the surface of the head is not flat. Two correctly machined surfaces should ultimately need no gasket for exhaust. Just bite the bullet and get the two parts correctly done and you won't fight it for the life of the car.

Copper RTV

another vote for Remflex

Ditto....And what I do to get my junk to seal, I red rtv the gaskets to the heads and let them sit 24hrs...

The manifold needs to come off anyway. 99% chance it's not flat. Perfect time to get it machined.
Doug

Fel-pro blue perma-torque gaskets here forever installed w/just a smear of grease and a couple re-torques..........no leaks ever BUT the flanges need to be flat..........

Remflex as well. I had a lot of problems sealing up some old headers. These worked great. They are not reusable though.

My vote as well.

I’ve got the remflex in last night but they are so thick, I’m afraid the nuts wont engage the threads enough. Do they squish a lot?

They do squish a bit but not a lot. Look at the pic I posted to AndyF's thread on the Milodon Sandwich Plate ... you can see the Remflex Gaskets torqued down and how much they squish (not much). I'm using Percy's locking header bolts that are 3/4" long (https://www.summitracing.com/parts/php-310014/overview/) and there is plenty of thread engagement. And I've had these headers on and off while reusing the gasket and never had a leak. I HATE header leaks ... they drive me nuts!! My heads are aluminum but the gaskets didn't stick when I removed/reinstalled the headers. My experience is that as long as you put them back on with the same headers and in the same orientation, they can be reused. They have a sort of non-stick graphite coating on them. If you are running iron heads with studs, you might have to put in studs that are just a bit longer. Not sure if they might stick to cast iron after a bunch of heat cycles.

I can’t use longer studs. It just barely comes off enough to get the manifold off the studs. The pass side is way close to the shock tower. This car is “killing me, Smalls”!!!!

Same here. Never have any leaks.