How to replace 1988 Toyota pick up heater core?

I have '89 pickup, and my advice would be get a couple estimates cause its a b----! Currently in the process, and if you are not prepared to totally remove all dash components, drop steering wheel, remove reinforcement bar just to get access to the core, then you may want to rethink! Its going to take time and a lot of patience to get it back right. I have about six hours so far, so I,m sure at least double to get it back. Wish I had gotten estimates! Goo Luck!