I just purchased the Playpen for my 2002 MDX, here's what I've found...
- I does fit without the extension. I believe the 2001 model MDX had its factory bars further apart and thus would require the extension.
- The old style (before 7/31/2002) attachment hardware does not fit very well. The bar saddle does not fit the factory rack correctly, this keeps the attachment clamp from being able to be closed. I removed the saddle and am now able to close the clamp but there was another problem...
- The upper bracket has a tendency to slip off the lower bracket due to a design flaw which is easily corrected with a pair of pliers (how lame). It will be quit obvious what the problem is when you see it.
- There is a new version of the attachment hardware that looks much better and may solve all of my concerns (see
http://www.thuleracks.com/thule/instructions/501532704, 840.pdf). I'm now in the process of trying to order these parts. I'll post back when I get them in.
Hope this helps.