Compaq 247320-003 - Deskpro 4000 - 5166 Model 2500/CDS Reference Manual page 17

Drive Position Configuration
Standard internal hard drive (2.4 GB or 3.2 GB)
Standard, 3.5-inch 1.44MB diskette drive or LS-120 Drive
Optional PD-CD Drive, CD-ROM drive, diskette drive, tape drive, or hard drive
(5.25-inch, half height)
Optional PD-CD Drive, CD-ROM drive, diskette drive, tape drive, or hard drive
(5.25-inch, half height)
Optional PD-CD Drive, CD-ROM drive, diskette drive, tape drive, or hard drive
(5.25-inch, half height)
The minitower model can house up to five mass storage devices.
To verify which mass storage devices are installed in your
computer, run Compaq Diagnostics for Windows or the
INSPECT utility. Refer to Chapter 8, "Using Compaq Utilities,"
for more information.