While our Ron Davis radiators are virtually identical in size and layout to the originals, I'll go against what it says on the site about it being a no-mod install. While they are indeed a drop-in, and use the stock (or stock 3-row replacement) mounts, you will almost certainly have to grind some material from the upper mounts to clear the radiator body.
The mounting points just happen to be exactly where the junction of the tank and core is, which can be the thickest point on the unit.
So it's still a very simple install, but you might still have to grind some material to "make" it simple! ;D
Here's an install I was checking out just tonight.
You can see that it fits after some material was removed from the stainless mounts. Hard to see in the pic, but the way the mount looks raised up off the radiator is just because the mounting "tab" is there holding it up.
Paul