I NEED YOUR HELP, WHAT IS THIS PART

Whilst doing a full detail on my truck last week I noticed the passenger carpet wet underneath my rubber floor mats. So for the past week I’ve Been trying to track down The leak. I did the full wiper valley seam seal and put everything back together, still leaking, finally today I was able to pull the padding up under the dash back enough to find the leak. This leak is up the firewall inside behind all the ac stuff almost up in the front right corner. This sealed joint has formed cracks and is now letting water into the cab. Anyone have any idea of what this part is and how the best way to get to it is. I do t just want to patch the holes and have it crack somewhere else later I rather re-seal the entire thing. Attached is a picture of the crack

 

Try this thread.

https://www.tacomaworld.com/threads/water-leaking-into-cab.523251/#post-21577889

 

I’ve been through all the threads and have found my specific leak. I have done all the fixes that thread mentions

 

dry that with a heat gun (or hairdryer)

slap roofing sealant on that

 

if he can get access to it from the other side, I'd do the outside.

I'd also do my best to cut out (or at least try and clean) the dirty spots of that sealant, and re-apply. Maybe get one of those plastic syringes with a small tip and inject sealant into the holes, rather than just covering them up.

 

Many body panel parts are joined by spot welds and sealed with a caulking compound. RTV black silicone works well at long term resealing spots like that