ECE Mounts on a 63 frame

[burlapen]

So I picked up a 4.8 gen III engine that I test fit to the frame of my 63 C10 yesterday. I used the ECE mounts and found that I had to grind a significant amount of material off of the frame on both sides to allow the tower side of the mount to reach the original holes. Also, the lower half of the towers did not line up with any of the holes in the crossmember. I thought I read that these were pretty much a bolt in deal other that having to relieve some material on one side of the pre 68 frames. Anyone else run into this?