The items that fit your Toyota Alphard (AH-10) are shown below.

The first generation Toyota Alphard has two different styles of radio.

The smaller versions are the standard Toyota radio size and just needs a pair of side bars to fit a double DIN radio into the dashboard. These original radios have a variety of different looks but are all the same size, the lower edge of the radio roughly lines up with the lower edge of the air vents on either side

The larger version has original sat-nav and the lower edge sits below the air vents, roughly in line with the hazard switch. These require a much larger fascia to change.