3/8 Universal Joint Progression
The sizes are about right.
First from the early 1930s
Second from the late 1930s and ran through WWII to 1948
Third is modern
The first Universal joint is from the early 1930s, the style changed in the late 1930s and ran through WWII. The last is a modern piece, in 1948 the style changes and ran through the late 1970s.
The difference between the F-80 and the F-80 is size. The F-80 is much bigger. There are very few early universal joints. It appears they were weaker and after years of use, they break. The F-80 is a much beefier universal joint.
Snap on Model number | Description | 1937 |
F-8 | A universal joint | 1928-1946 |
F-80 | A universal joint | 1936-1946 |
FU-8 | Universal joint | 1948-1978 |
FU-80A | Universal Joint | 1948-1978 |
FU-8A | Universal joint | 1953-1978 |
FU-8A | Universal joint | 1995 |
FU-80B | Universal Joint | 1995 |
FUB8 | Universal joint | 1995 |
3/8 Flexockets
1929 introduction – shows thick set with tapered angles
This is the series introduced in 1929. These are smooth heads and have tapered sides. This seems to have changed to a slimmer socket in the 1931 catalog. The 1933/35 sockets are slimmed down further. The 1937 has the knurl head styles and changed again in 1939. The 1939 – 1946/7 styles remained unchanged.
3/8 Flexocket 1939 Style Change
Left is the catalog drawing from 1939 vs the photo
Flexockets | Size | Date Range |
F-12 | 3/8 | 1929-1946 |
F-14 | 7/16 | 1929-1946 |
F-16 | ½ | 1929-1946 |
F-18 | 9/16 | 1929-1946 |
F-20 | 5/8 | 1929-1946 |
F-22 | 11/16 | 1933-1941 |
FU-22 | 11/16 | 1936-1946 |
F-24 | ¾ | 1936-1946 |
3/8 Flexocket 1948 style change
Left is the catalog drawing from 1948 vs the photo
The FU series is easy to ID, they have two ribs in the head and the diameter of the dowel pins increased. The head diameter and length is the same.
Flexockets | Size | Date range |
FU-10 | 5/16 | 1948 |
FU-12 | 3/8 | 1948 |
FU-14 | 7/16 | 1948 |
FU-16 | ½ | 1948 |
FU-18 | 9/16 | 1948 |
FU-20 | 5/8 | 1948 |
FU-22 | 11/16 | 1948 |
FU-24 | ¾ | 1948 |
FU-30 | 15/16 | 1975 -1995 |
In the FU A series the dowel pin ends are no longer exposed. There is no other visable change I can see
Flexockets | Size | Date range |
FU-10A | 5/16 | 1950, 1978 – 1995 |
FU-12A | 3/8 | 1950-1995 sporadic |
FU-14A | 7/16 | 1950-1995 |
FU-16A | ½ | 1950-1995 |
FU-18A | 9/16 | 1950-1995 |
FU-20A | 5/8 | 1950-1995 |
FU-22A | 11/16 | 1950-1995 |
FU-24A | ¾ | 1950-1995 |
FU-28A | 7/8 | 1960-1995 |
3/8 Flexocket 1950 single and double broached
Left is the catalog drawing from 1950 for the FU and right FS
The FS series is a single broached FU series
3/8” Drive Single hex Flexockets | Size | Date range |
FS-10A | 5/16 | 1950-1995 |
FS-12A | 3/8 | 1950-1995 |
FS-14A | 7/16 | 1950-1995 |
FS-16A | ½ | 1950-1995 |
FS-18A | 9/16 | 1950-1995 |
FS-20A | 5/8 | 1950-1995 |
FS-22A | 11/16 | 1967-1970 |
FS-22 | 11/16 | 1960, 1978-1995 |
FS-24A | ¾ | 1967-1970 |
FS-24 | 13/16 | 1960-1995 |
FS-28 | 7/8 | 1978-1995 |
FS-30 | 15/16 | 1978-1995 |
FS-32 | 1 | 1978-1995 |
3/8” Newer crowsfoot wrenches
Catalog drawing from 1965 of a bolt flex socket
Bolt Clearance Flexockets
Introduced in 1965 this is a deep socket and a universal joint combination. Bolts found on caster-camber fittings, intake and exhaust manifold bolts
Flexockets | Size | Date range |
FSU-12 | 3/8 | 1978 – 1995 |
FSU-14 | 7/16 | 1965, 1975 – 1995 |
FSU-16 | ½ | 1965, 1975 – 1995 |
FSU-18 | 9/16 | 1965, 1975 – 1995 |
FSU-20 | 5/8 | 1965, 1975 – 1995 |
FSU-22 | 11/16 | 1975 – 1995 |
FSU-24 | ¾ | 1975 – 1995 |
Deep Flexockets | Size | Date range |
FSU-10M | 10mm | 1970 |
FSU-11M | 11mm | 1970 |
FSU-12M | 12mm | 1970 |
FSU-13M | 13mm | 1970 |
FSU-15M | 15mm | 1970 |
FSU-17M | 17mm | 1970 |
FSU-19M | 19mm | 1970 |
FSU-22M | 22mm | 1970 |
3/8 Whitworth sizes
Whitworth | Description | Date range |
WFU-99 | ¼ | 1958 |
WFU-100 | 5/16 | 1958 |
WFU-101 | 3/8 | 1958 |
3/8 Metric Variants
Stock Number | Size | Dates |
FSU-10M | 10mm | 1965-1967 |
FSU-11M | 11mm | 1965-1967 |
Stock Number | Size | Dates |
FU-12M | 12mm | 1965-1967 |
FU-13M | 13mm | 1965-1967 |
FU-14M | 14mm | 1965-1967 |
FU-15M | 15mm | 1965 |
FU-16M | 16mm | 1965-1967 |
FU-17M | 17mm | 1965-1967 |
FU-18M | 18mm | 1965 |
FU-19M | 19mm | 1965-1967 |
FU-22M | 22mm | 1967 |
Left is the catalog drawing from 1948 vs the photo
More modern example