J Man,
What year, model/size, and brand of truck are you referring to? If it is your "regular" truck, you might want to put this information in your Profile.
Bill, is referring to most Chevrolet trucks. If you are referring to a COE/LCF and/or GMC trucks, the bigger GMC trucks have additional differences in cabs and sheet metal.
If you are looking for used parts, check out the Swap Meet.
In any case, parts specific to larger trucks are much harder to find new or used.
Tim
