I found this on another forum site.
Tools Need: adjustable wrench, some sort of cutting tool, I used a zip disk, tape measure, tape, pliers, paint, grinder or sanding wheel
Ease of Install: easy
Estimated time to install: 1 hour to do, then extra for paint to dry.
remove antenna from car. at the same time also measure where you want to cut it and mark it with tape. I chose 6" form the base.
clamp antenna in a vise and cut at the tape edge, tape both sides unlike me. then the wire wont unravel.
Clamp the other end of the antenna in the vice again. with the ball on top.
now take your pliers and twist and pull on the ball. it is a tapered fit. it will pop off takes some effort. so don't be a sissy.
grind the short end of the antenna down to fit the ball, don't make it to slow of an angle or it wont stick properly, it has to be a tight fit. now turn upside down and hit the ball on about 4 or 5 times to makes sure its on good.
now paint that sucker, make it look good.
and you done.