This information courtesy David Thompson
In regard to the new HO Scale Stewart model:
Starting off, VO-660 production tracks with VO-1000 production with two
main exceptions: the side radiator intakes were discontinued in 11/41 on
the smaller VO, and VO-660 production was suspended from 11/42 to 12/44.
(scroll down to the bottom for phase descriptions)
Bad news first: none of the three versions are accurate. The 'Phase I'
has the side radiator intakes of Phase IIa production, but it should also
have the earlier cab with the flatter roof and it should not have the
larger radiator expansion tank. The 'Phase II' is good for late '43 and
early '44 production, but there was no production at that time. The
'Phase III' is correct for 2/45 and later, but it should have the later
angular side sill corner tabs.
The good news is that all three provide parts for kitbashing VO-1000
and early DS 4-4-xxx variants.
- delivered in black and white/aluminum, lettered Southern Pacific Lines,
- received standard orange and black switcher Tiger Stripe paint, lettered Southern Pacific,
- later orange and black 'Halloween' paint, lettered Southern Pacific. Neither received the 1958 scarlet and gray, even though they survived until 1963.