Let's make this a little easier to nail down here. What are you building and what are you putting in it?
For example, I'm building a pair of Sig Kadet Jr's with an OS 25FX in one and 35AX in the other, both controlled with 5 servos using a Futaba 9C. The instructions tell me what to put in and when but, unfortunately, don't say anything about allowing access to the fuel tank area after the servo tray is installed. When I built the kit(I'm plans building two more using the hardware that came originally with the kit on one of them), I found that the fuel tank was trapped because of my servo tray being too high and too far forward.