Sdgthy at optonline.net informs us in thread »Measurements of ONT, power spply & batt. of the following dimensions:

Tellabs
The 610(x) ONT is H15.8" x W12.5", D5.05"
The 611 ONT is H16.33” x W12.69” x D4.5”
The BBU is H7.5" x W9.5" x D3.25"
The power supply is H2.5" x W8.5" x D2.0"

Motorola:
ONT1000GT2 - H11.5" x W10.4" x x D3.0"

Newer equipment may be supplied, including an "all-in-one" ONT, BBU and PSU.

clnelson informs us that:
"Verizon may install a MoCA Amplifier if you have long RG6 runs and/or many FiOS TV boxes. The MoCA Amplifier is H1.0" X W3.25" x L5.0" and is powered (through a short RG6 cable) by a small "brick" power supply (H1.5" X W2.0" x L2.5") that directly plugs into a 110V plug."