That looks like 1960 two wheel drive 2 ton cab and chassis built in Oakland 3425th off the line to me.
C= 2wd conventional cab
6= 2 ton
3= ? perhaps wheelbase
3= Cab and chassis
The rest is the build number starting at 100001.
The "3" in question is in fact the wheelbase...157".
The other thing I would add is that by 1960 calling trucks 1-1/2 or 2-ton rated was being phased out as GVW ratings for any given series could differ by thousands of pounds based on what tires and suspension got installed, so in this case the "6" would be the Series identifier (60 Series).