That adapter is also 7/8 thick and the bolts have a 1/2 to bite into. You're right 97 SL320, the Ford bolt holes aren't tapped yet. It's going back in the mill when I get a tap. I was dumb and forgot I had only put in easy numbers in for the Merc holes when I drew it so I'd know what it looked like and never put in the real values, and so it's got to go back in the machine anyway

I thought that my truck had a removable front clip like a Bronco but nope! It's all welded together. I guess I'll just drill out all the spot welds on the radiator support instead. I've got a few 1/2" HSS spot drills but not an actual spot-weld bit, don't see why it wouldn't work though so I'll give it a try