[Vortec350S10]

I'd definetly say it's the heater core- happened to me last fall in my s10. As for replacing a camaro heater core it's not too fun. Remove dash pad, E brake handle, shifter knob,entire center console, unbolt dash speaker brackets, dash nuts near windshield, drop steering column, remove heater box cover under dash, then at least you can sorta see the heater core... then take out the heater core bolts-7mm and disconnect heater hoses right near firewall on heater core. Then you should be able to get it out! Good luck, PM me if you have any questions