My 69 RS didn't have any sealer either.
Attached photo is the only one of the fan side of the motor/blower assembly prior to cleaning things up. Second picture is of the outer heater box cover where the motor/blower assembly bolts up. If you look closely, no evidence of sealer on either the blower flange or the outer heater box cover.
That being said, when it went back together, it did get some sealant.