A hovering object in the vicinity of "The Lady of the Mountains".

Travelling North on interstate 15, just past Butte on a streach of road going uphill. I noticed a sphere hovering very near a statue referred to as the "Lady of the Mountains". It was, what is commonly reguarded as, disk shaped with rounded dome and also rounded in a congruant fashion on the underside. Driving up the mountain I noticed that the craft was yellowish in color, gently changing it's hue to an orange and then back again. It remained stationary till I drove under and it disappeared due to my forward progress. Thinking it was one of those safety devices used to warn low fling aircraft of hi-tension wire in the area, I was not overly suspicious. As I was coming back using the same route on my return trip a few days later I would check it out as to placement of the devices. To my surprise on that return, day-trip this time, I encountered several grey vans with strange looking antennaes emmanating from them on the mountain overlooking Helena going south. What was even stranger were the personel. They were seemingly a bunch of "goodlooking" guys ages between 25 and 30 scurrying around in bluish-grey overalls. Going further south past Helena about 10 miles north of Butte, I again noticed similar vans with personel fitting the above description. Guess what? When I got to the place where I saw the object there were no high tension wires, nor were there any warning devices strung along any of the smaller cables crossing the hi-way at that point. Even stranger was the reoccurance of vans further to the south, before one reached the town of Dillon, Mont.
Date of incident may be approximate, although the witness does not indicate that fact.  PD