[Police] andy's guitar preamp

does anyone know what preamp is/was in andy's telecaster? i'm assuming since it was the early 70's when the preamp was put in, that preamps as such, for internal guitar mounts, weren't common place and that it was a retro fit from say an MXR micro amp pedal, or something of that nature. the reason i ask is that i am building an andy tele copy and would like to make it as exact as possible. thanks t