Since it is for his son, the son can go to any Social Security Office and request the the information. Other than the very basics (name, date of birth and death, and number) there is little else available to the general public. However, as his son, he will be able to get the information Harold supplied when he applied for his Social Security card right through his earnings history.
Here is the application he will need to use:
Please let me know if you need more information about this.