I put a Heil element in my old D104 head about 2 years ago and I highly recommend it - works fine for me. I had to use some foam to keep the smallish Heil element in place - that old crystal mic element is much larger and all the empty space had to be filled with something. 73, Don W3FPR ----- Original Message ----- > I'm seriously considering installing a Heil element in my 50 year-old > D104. > > Bob, N7XY >