center of drove shaft to front w arm mount is 4 3/4" back. front w to center pivot is 11 1/2" apart. front w to rear scissor is 27 1/4". all center to center. inside top of tunnel down to front w is 5 3/8". center pivot down 4 1/8". rear scissor is down 6 1/8".
pretty sure the trailing arm pro action skids are a bit wider than that enticer tunnel. seems like they are just over 16" wide, perhaps almost 16 3/8".