You know the Delivery Truck in SketchUp Sampler.
The rear can change.
Do you Know how to do that?
No
Well I can give you the way!

1. Make a shape that may change i.e. Interchangeable text. Make it a component. Call it set1
2. Make a different one in it's place. Call it set2
3. Combine them together. Make sure set2 is hidden. Call it set
4. On component attributes, set must have the "Show" command on it. Type 1 on the next one
5. The script for each component should be
   HIDDEN | =IF(set!Show=1,0,1) (1,2,.......N)
   ONCLICK | SET("set!show",2) (2,3.....1) Important!! The last one must have 1 or it won't work
6. Interact and it should change!

Here is an example

set function.skp

Chris, thanks. I'm currently making a bus with a ramp and your formula worked!

I had to figure out that I had to invert the X and RotZ formulas to make it work!

Rampsystem.skp