I need to rent/lease about 7 half ton, 4 wheel drive, preferably extended cab pickup trucks for a construction project to last about a year to a year and a half in So Cal. Does anyone know of a company who specializes in contractor rentals for this period of time that can offer a good rate?

Hello .. Welcome to the forums...
Can't point you toward anyone local to you.
Some suggestions... A local truck dealer. The fleet manager would have some options. A few national rental compaies come to mind... Ryder, Hertz, ... also contact your local construction equipment rental companies.