Any Unity spotlight can be fitted to just about any vehicle, but the newer lamp off a Crown Vic probably won't work on your truck as the length of the shaft may be so long the inside handle will collide with your steering wheel. I believe the correct length is 12" from the pivot point of the head to the pivot point of the handle.
The attached thread may prove helpful for further details:
http://67-72chevytrucks.com/vboard/s...ight=spotlight