Its hard to tell from pic. I've never heard of this before either. I wouldn't use jb weld if it was me to fill in a dip. If anything maybe rtv..

 

If this is what you are talking about it a blind hole..
Just sand it down and put alittle sealer on it .


monte080_zpsb7324c04.jpg

 

First - I moved this thread to an appropriate section.

Second - If there is a hole in the LIM, the easiest thing would be to just hit a junk yard and replace it. The 3800 is so common should be easy to find.

 

Tis the blind hole but I believe the gasket covers the water port on the intake side, thanks for the input guys, I will pick up some high temp rtv today. Tis the wife's car, and she must be kept happy, happy, happy at all costs. Personally, I am still driving a gmc safari van after 14 years. Had to repl a tranny three years ago, after reviewing comments on the bbb site, I ordered one from out west and it has done a bang up job. MC sure is a good looking car though.

 

Guys, it also ate a hole in the head just below the gasket on the firewall side!

 

Picked up a lower intake from the junk yard this morning for 26.50. Had no idea it would be that cheap. A year older, I will check all the holes and ports etc, peeled the gasket back on both sides and no erosion holes. Hmm, wonder if that was a bad casting. Thanks for the info.