Blue Jay, I installed mine in my 91 D350 about 3 or 4 years ago and even with the excellent instructions that come with the tank it is a *****. Especially if you don't have any help. If I had it to do over again I would make an appointment with the dealer and have them install it. It took me two full days to complete the job.
Then about 6 months later I had to remove the tank to have the bed Rino Lined. I have read that it takes their installers about 3-4 hours to do it in their shop. LOTS OF WORK. You may welcome the challenge.
Walt.