Semroc MMX Blue Bird Zero Build, Part 3, Body Tube Lengths

Step 3 says to "Take one of the body tubes" and mark it for the fins. It doesn't specify which tube to mark.
Choose the shorter tube, it should be 5 1/4" long. Mine was 5 3/8" long. The upper tube was 6" long. It should probably be closer to 6 1/4" long to be scale.

I cut the long blue coupler down to a 1" length. It just seemed too long to me.

Glue the coupler halfway into the top of the lower 5 1/4" tube.

GOTCHA: Step 8 has you glue the two tubes together.
Don't glue the tubes together, leave them separate for now. You can paint the lower body section white and the upper body light blue. Then glue them together - no masking!