Jaime Hernandez: The 1976-P Clad Biccentennial Quarter is a one year type, also known as a Type 3 design. 1976 Clad Quarters were produced at the Philedelphia Mint and at the Denver Mint.
The 1976-P Clad Quarter is the scarcer of the two in mintage and in high grade condition.
The Mint also produced a business strike 1976-S Biccentennial Quarter composed of silver or a Type 4.
For the Proof Bicentennial Quarter the Mint also produced two different types. The Type 3 was produced out of a Clad composition. The Type 4 Bicenntennial Proof Quarter was composed of Silver. Both proof quarters bear the "S" mint mark since they were produced at the San Francicso Mint.