Bob,
Below is a list of National serial numbers that I posted last October. Thank God for the "cut and paste" and "search" functions!
The list does not include numbers from the 1930's.
Yes, these come from Gruhn's book:
Valco/National serial number plates, 1941 - 63 (from Gruhn's Guide to Vintage Guitars)
The number ranges shown are approximate
1940 - 42 ----------- G suffix
1947 ---------------- V100 - V7500
1948 ---------------- V7500 - V15000
1949 ---------------- V15000 - V25000
1950 ---------------- V25000 - V35000
1951 ---------------- V35000 - V38000 X100 - X7000
1952 ---------------- X7000 - X17000
1953 ---------------- X17000 - X30000
1954 ---------------- X30000 - X43000
1955 ---------------- X43000 - X57000
1956 ---------------- X57000 - X71000
1957 ---------------- X71000 - X85000
1958 ---------------- X85000 - X99000
T100 - T5000
1959 ---------------- T5000 - T25000
1960 ---------------- T25000 - T50000
1961 ---------------- T50000 - T75000
1962 ---------------- T75000 - T90000
G100 - G5000
1963 ---------------- T90000 - T99000
G5000 - G15000
1964 ---------------- G15000 - G40000
1964 - early 68 ----- sticker w/"1" prefix
early to mid 1968 --- sticker w/"2" prefix
dougb
www.dougbsteel.com