I was up at the farm today and had a look underneath. It is a Spicer 3152.
Looking at the axle shifter I see it stamped "Used SAE 10" on the cover. The small filler plug is very near the bottom so it must not hold very much oil.
Also, looking at the differential I couldn't find a drain plug. I see the fill but wonder how I drain it. Would removing one or two of the lower front bolts allow it to drain?
