To find the volume of the rectangular pyramid with a base and height congruent to the rectangular prism, we can use the formula for the volume of a rectangular prism and the formula for the volume of a pyramid.
The volume \( V \) of a rectangular prism is given by:
\[ V = \text{length} \times \text{width} \times \text{height} \]
For the rectangular pyramid, the volume \( V_p \) is given by:
\[ V_p = \frac{1}{3} \times \text{base area} \times \text{height} \]
Since the base of the pyramid is congruent to the base of the prism, the base area can be expressed as:
\[ \text{base area} = \text{length} \times \text{width} \]
Thus, the volume of the pyramid can be written as:
\[ V_p = \frac{1}{3} \times (\text{length} \times \text{width}) \times \text{height} \]
Now, we know that:
\[ \text{length} \times \text{width} \times \text{height} = 27 , \text{in}^3 \]
This means:
\[ \text{length} \times \text{width} = \frac{27}{\text{height}} \]
Now substituting this into the pyramid volume formula:
\[ V_p = \frac{1}{3} \times \left(\frac{27}{\text{height}}\right) \times \text{height} \]
This simplifies to:
\[ V_p = \frac{1}{3} \times 27 = 9 , \text{in}^3 \]
Thus, the volume of the pyramid is:
\[ \boxed{9 , \text{in}^3} \]