I have a 1956 Gibson Southern Jumbo that I had a cheap soundhole pickup installed in a couple of years ago. I decided to upgrade to a M1a. I didn't expect any problems since I had a luthier install an end pin jack to make a semi-permanent installation for the old p/u and the hole was already there. First, I found that the old end pin jack was a tapered one that pressed into the original tapered end pin hole. I was prepared for that and was ready with a reamer to ream the tapered hole to the 1/2 inch one required for the M1a. I was not prepared, however, for the fact that the threaded shank of the M1a strapjack was about 1/4" too short to pass thru the tail block of the vintage Gibson.

Fortunately, after a period of sheer panic, I realized that if I took ALL the washers off the strapjack the entire assembly would pass thru the hole. I was able to slip an appropriately sized flatwasher down the body of the jack and epoxy it in place to form a retainer that allowed the jack to protrude the right amount for all the external hardware to fit properly.

I don't know how unusual this problem is but I wanted to pass it along in case anyone else runs into a similar situation. I was also wondering if there is such a thing as an "extra long" jack available for guitars with thicker tail blocks?