Well actually it seems unlikely you will find Spanish troops on the front alongside other NATO members.
Basically, "no troops were to be deployed outside of Spain on a sustained basis" and the command structure is not integrated into that of the rest of NATO.
http://www.country-data.com/cgi-bin/query/r-13103.html
It would seem their role in the event of WWIII would be to secure a strategic base of operations (ie their own borders) in order to facilitate counter attacks upon the PACT forces when the rest of Europe was lost.
Spain, the ultimate REMFs/pogues...