Combined info from TX Dth Idx and SSDI (Soc Sec Dth Idx):
Morales, John, b 5 Jun 1921; d 21 Jan 1971 Harris Co, TX; SS card issued in TX.
Morales, Pieda, b 19 Jun 1924; d 10 Apr 1998 Harris Co, TX; last residence Houston, Harris Co, TX; SS card issued in TX.
You can obtain a copy of their death certificates which should show the names of the parents, accuracy only as good as the knowledge of the informant.On the other hand you can obtain a copy of their application for Soc Sec card and which each filled out, and that should show the names of parents, place of residence at time of application and other data.
If I understand you correctly, John and Lupe are brothers?If so, one may have used their fathers surname the other their mother's name as often is done in Mexico.Have you contacted Lupe to ask about his surname being Gutierrez?Sounds like you should talk to your cousins and family members, glean what you can from them.