I have sandwich adapter from Hardin marine part # 6257917. I installed new oil cooler cuz mine was missing from previous owner. Question is do I have to remove the stock oil filter threaded portion from block? Or does this adapter just bolt right on over stock oil filter mount?

this one

Big Block Chevy Gen 5 & 6 Side Entry Remote Cooler Sandwich Adapter - CP Performance

That's the one. I think I figured it out and I do need to remove the tread insert .

yes...remove...hope you can get to the filter...

Got it out and installed sandwich, plummed all lines with -10 pushloc fittings and works great.need to test run now. my filter is easy to get to so no issue there