I was in the local home center the other day and spotted an attachment for my Dremel Motor Tool. The attachment allowed the Dremel to work like the Zip-N-All. After looking at it for a few minutes I determined that I could use it to help me grind T-Jet body posts when lowering a body on the chassis. The great thing about this is you can remove post material and still maintain a square post. If you're interested in how I did this then take a look.
I first needed to create a mini table to rest the car on while grinding the post. I use three pieces of styrene to provide a table and some rigidity.
Then I had all three pieces and all I had to do was put them together.
Take a close look at the attachment... you can adjust the level and then tighten the set screw to stabilize it.
With this set up you can quickly remove the post material and still maintain the squareness of the post so the chassis will be square with the body.