1987 300D fuel tank removal?

[Diesel Dan]

Hi folks. I've decided to get my fuel tank steam cleaned and am in the process of removing it. Quick question: is it only held in by the four nuts accessed through the trunk, or do I have to remove the rear seat to get at something from the inside of the car? I removed the four nuts from the trunk side and the tank is not coming out. I don't want to force it and break something, and before I go through the hassle of removing the rear seat, I thought I'd ask. Thanks!