* With the rear seats up: A 6x9 sheet of plywood or similar material is unlikely to fit in the rear door opening of *any* Chevy Trailblazer with the rear seats in their upright position. The opening is typically much smaller.
* With the rear seats folded down: It *might* fit, depending on the year and model. The larger the rear cargo area, the better the chances. However, even with the seats down, it's likely to be a tight fit and may require some maneuvering.
To be certain, you should:
1. Measure the width and height of your Trailblazer's rear door opening.
2. Compare those measurements to the dimensions of your 6x9 sheet.
If the dimensions are close, consider also the depth of the opening. You need enough space to easily slide the sheet in. A slightly oversized sheet may not fit, even if the measurements seem promising.
