Shown on the schematic as polarized, so I suspect they are large mfd, low voltage electrolytic type? Apparently 1.5 ohms is their impedance at 120 hz. Using the below calculator I came up with 880 mfd to get close to 1.5 ohms. Looking at that Aerovox part number(PRS6/1000) I'm going to guess they're 1000 mfd @ 6v. I'll see if I can find that AV number in an old catalog.
http://www.allaboutcircuits.com/tool...ce-calculator/