I'm not sure what you mean by a date range of "1 day and 1,095" -- do you mean the NUMBER of days between 2 dates can have that range but no more and no less or do you mean that the dates range from Jan 2, 1960 ( internal number value 1) to Dec 31, 1962 (1095 internal number value ).
Are your date variables numeric variables or character variables? If you run PROC CONTENTS on your SAS dataset you will be able to tell whether your date variables are character or numeric. It would also be useful to know whether your variables represent the number of DAYS since Jan 1, 1960 (simple date variables) or whether your variables represent the number of SECONDS since midnight on Jan 1, 1960 (a datetime variable).
From the SAS Language Dictionary documentation, have a look at using the DATA step function INTCK to count between two dates - weekday is handled with this function (coded as argument1 along with your two SAS DATE numeric variables).
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