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

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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

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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

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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

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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

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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

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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

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Left is the catalog drawing from 1948 vs the photo

More modern example

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