1972 radio
 

hi i have a 71 blazer and just got a am/fm radio at a yard sales for 2$ not sure if it works but will fill the hole anyhow and if does work bonus find it says gm72 on the sticker on the side... im asking if anyone has a diagram for the wiring so i can test it out? as in the pos /neg and what wires are for speakers? thx :chevy: