simple 3mm blue LEDs for each of the engines. They have to be drilled out. It's easiest to remove the glued on end caps and place the leds behind them, then glue back on.
I created a channel for the cables just above the locator pins, and also hollowed out the cockpit/engine part. This piece houses the light and sound module by default, which has to be removed in order to fit the wiring.
Sacrificed a Revell Snowspeeder for the cooling unit that's missing from the model. The size is pretty much perfect, but it still takes lots of filing and sanding