[Zeratul1320]

Eh... it doesn't quite work that way, I tried that myself and I was having one hell of a time figuring it out. It works like this.

1. open up the bumper (or transmisison support bracket or whatever you want to extend or retract)

2. Right click on Base1 under filename.ipt and select Edit Solid
This is where you can extend or contract the part.

3. Select Extend or contract body and chose the plane you want to expand or contract it on ie. the end face of the part

4. Enter the distance, to achieve the correct size for the bumper select 20 (yeah its weird) then hit ok.

5. Measure the length using the measure tool just to check, then hit return and save it as a new file.

There you have it. You can do the same for the pistons but you need to do it to several of the components.