<nitpick>
The trolley poles on SN freight motors were generally only used on the ferry "Ramon", as its overhead couldn't handle pantographs--normally the panto was used wherever there was overhead. Originally the 650 and other North End (Northern Electric) cars just had trolley poles, but after the merger with OA&E the pantos were installed.
Uncovered overhead third rail was used on the North End (between Sacramento and Chico) in rural areas, switching to 600-volt overhead in towns. Third rail was not used at all on the South End (Sacramento to Oakland), including at the Naval Weapons Station. Even SN's Birneys could be fitted with temporary third-rail shoes to allow them to make the trip north to Chico for shopping.
</nitpick>
Nitpicking aside, I've got one of those Cannonball kits and it is high on my list of Things To Make Real Soon, even though the 40-ton version is way too small to accurately depict an SN switcher...I'm too impressed with Gerold Eckl's version of the same kit (made for his semi-freelanced railroad based on the SN) to worry about those sort of details! My main worry is being able to fit all the tanks, brackets, widgets, doohickeys and whooziwhatsises that SN stuck all over their freight motors onto that little 40-ton chassis...and if anyone asks me about the small size, I'll just hit 'em up for the $500 that the brass one would cost!