The 1986 454 and other similar years have an oil cooler, and it interfaces to the engine with an oil cooler line mounting adapter at the position of the oil filter.

I had to learn about this with the work I am engaged in on my Barth now. I had to remove the adapter to get access to the oil pan bolts. The adapter is secured to the engine block with two bolts. After removing these bolts, I had to use oil filter pliers to gently wrestle the block away. There is a gasket there, and there is an O ring there.

The gasket and the O ring will be replaced. The mounting block is GM part 14088848, the gasket is 326100, the O ring is 14015353.

I found that the bolts and the oil filter connector were "hand tight". On future oil changes, these are going to be snugged up.

At www.gmpartswiki.com, I found the picture I am showing here. Because GM changed the designation of the CK series of pickups to "RV", it makes google searches of that site a little more difficult for us motorhome guys. If I spent more time, I would have found the P30 page, but this diagram was helpful in understanding the connections in my P30 case.

Matt