Print the head with support.
Catbodyf is the "regular cat" configuration, with all four legs moving forward.
Catbodyproto allows you to install either walker mechanism forward or backwards. I thought running them in opposite directions would result in enhanced bobblehead action at the expense of forward motion, but this was not the case in real-world testing. Removing the mechanisms to switch directions is also much more difficult with the tolerances of my latest Replicator-printed body.
I used the 35mm spring pin for the neck and the 75mm snake pin for the tail. I did not alter the parts, they are interchangeable with the other parts at http://www.thingiverse.com/thing:17725 so if you'd rather make a giraffe cat, you can.