Where is the front seal on a transmission for 1994 Chevy blazer s10?

The front transmission seal on a 1994 Chevy Blazer S10 (assuming a 4-speed automatic 700R4 or 4L60E transmission, the most common) is located at the point where the transmission's input shaft connects to the torque converter. It's essentially on the very front face of the transmission, behind the torque converter. You can't see it without removing the torque converter.