The below remark by Coastiejoe came from the above link. I think he's on to it.
My signal light seems to have an intermitten problem. Some time it cuts off, and somtimes it works. I tried setting the column to a different position but that did not solve the issue. I have to keep an eye on it. I think I may have to take it to the dealer for this one.
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re: 01 SportTrac Tailight Bulb Replacement by Coastiejoe,10/25/2006 14:09 ET
Before you do that, tilt you column and see if the light comes back on and works properly.
If so, you have the infamous wire harness issue in the column. If not, then go for changing the bulb...