According to Andy Mark drawing .pdf of C Channel Flat Am-0202
http://d1pytrrjwm20z9.cloudfront.net/c-channel.pdf,
You should see .375 holes at 3.25, 4.25, 13.25,14.25, 17.5, 20.75, 21.75, 30.75, 31.75. Ordinate dimensioning is really good for verifying hole position on the model.
You should be able to download this chassis
http://blogs.solidworks.com/teacher/...-a-robot-.html and import the C Channel.
I used am-0202 last summer and the Andy Mark numbers were true.
Marie