[87chevy.com]

Working on my 87 Silverado, with the motor out, decided to clean the firewall up. Noticed some rust colored runs in the center of the bulkhead seam above the trans tunnel. I removed the wiper cowl and screen and found the factory seam sealer started to deterioate. After picking at the seam seal material for a solid 30 plus minutes.. decided to surf the web for an easier way to dissolve the old seam sealer.

Some searching found say brake cleaner, gasoline, good off.. having tried either yet.
But, when I get it out.. what's the best way to get new seam sealer in there.. doubt there's no chance of getting the applicator gun in there... looking into the self leveling stuff since its the thinnest and would possibly get further in the joint. One idea I came up with is to squeeze out the mix into a syringe and then apply it...

Looking for advice from others that may have tackled this.

Thanks,
Clint