Whenever I export a rendered composition from After Effects CS3 and import the file into AVID Xpress Pro 5.8 the resulting import is squished and shorter than the rest of my footage that is captured directly in it. 

I have exported from AE CS3 with the AVID QT Codec, my files are squished and I have to adjust scale to 113 vertically in order to make them fit.

16x9 DV NTSC footage.

 I haven't found a format, resolution or anything that I can import into AXP that isn't shrunk like that.

I am working in a 30 NTSC file, both 4:3 and 16:9 are the same thing, squished videos.

in SD, you need to create your 4 x 3 comps at 720 x 486, Then, in Avid, your import settings need to be 601 non-square. Is that what you are doing?

In your 16 x 9 comps, what frame size are you using?

 Let me try that and get back to you.

 16x9 comps are 720 x 480 NTSC D1 DV

Right, they need to be 486 ONLY if you are working in DV resolutions in your Avid.

 That worked, thank you so much.

Also, I exported as a AVID 1:1 MXF so I will try a few things and see what works best for my workflow.

You are one of my heroes on this forum, you save many lives...

 did you mean to say 486 or 489?

486. Typing in the dark again.....

 Groovy, thanks.

You have been blessed by the editing gods. 

Wish I was you.....  I just keep getting the pooey end of the stick..

You have just washed that end for now.

 Well that was the smile I needed today...thanks. Hopefully you'll get nothing but clean sticks from here on out....

 I am working on some new projects that are forcing me to use more of the capabilities of Xpress Pro. 

Thank you for the wisdom.