John,
Just to add a little extra, hit the button down just before you need it. I've done it a little too fast sometimes and didn't allow it enough time to shift. There is a very small window to both let it shift and eliminating the "grinding" sound. Once it is perfected you will be shifting it with just a little "click".
Also, we have a similar subject going under "Making my 69 Chevy Dump go faster" for some more interesting reading.
Bill
