Vetnat,
Jolly from the 60-66 club - used to sell a neat little tool that will allow you to push up on both clips at the same time to allow the bottom of the lens housing to pop out. You can do the same with a large bladed screwdriver or 'chisel' (1" wide). You have to do this from the bottom of the housing, you push against the lip of the hood edge (nothing to give you leverage from the top side) Pop one side lose, and them the other, have someone hold onto the front of the housing so you can use both hands.
Once you remove the housing and while on your bench, you can use a Dremel tool to SLOWLY grind the back side of the rivet, (SLOWLY means - grind, cool with water, repeat) if not, you take a chance of starting to melt the lens from the excessive heat. A drill will work as well, but the same issues with heat will happen.
Once the lens is removed, you will need to replace the old dried up gasket, the after market truck places sell a close replacements, but I med mine from gasket paper from NAPA.
You should be able to see mine here.
http://s1299.photobucket.com/user/j...ens_zps36516371.jpg.html?sort=6&o=12
