Is there a cabin filter on a 77 Silverado?

[slam59]

My wifes 77 Silverado with a 454 has low air flow coming from the a/c/. It sounds like its blowing hard but it really does not blow out hard like most do. I read awhile back about people cleaning theor evaporator core and putting new filters on the cabin filter. Did the 1977 years of Silverados have a cabin filter? Anyone have pics of theirs torn apart showing the mess that accumalates in there restricting air flow? I remember one site had pics of different peoples torn apart and it was unreal what stuff was in there. They said after cleaning it all out it was night and day difference how much more air flow came out when the a/c was on.