Hello Gene,

Recent research has (the 1959 Chev truck manual) shows that:
the 3100, 3200, 3600 and 3800 have a 1.37 internal diameter steering cylinder
- the 4000 thru 8000 models have a "2" internal diameter steering cylinder
-9000 & 10000 models have a 2.375 internal diameter steering cylinder.

Those models have different flow rate pumps to correlate with the ram.

Check out the manuals and they may give you more insight

Mat


1958 Viking 4400