3/8 Extension differences

F-series logo and style progression

Extensions
The style of the extensions changed, but the listings really do not reflect this.  Shown in the top picture is a full set of extensions with WWII.  Most are not date stamped, but they still can be dated. The next 2 photos show the heads and the logo differences.  The earliest extension heads are un marked (these have labels on the shafts). The late 1930s (1937?) changed the head style through 1948. The FX heads have 2 ribs and are 1948 – 1978?

The FX-20 ran through 1935 – 1953 and changed heads through the life of the tool.

The 3rd photo from the top shows the same order of the squares. There is a noticeable rib in the earliest example and random variation after this. The last one is different. It is an industrial extension and does not have a friction ball, but a rod. This “locks” the socket in place and is not change friendly (But locks the socket on for tight areas). 

The last photo shows 3 logos of the early (pre 1937) extensions. We know these are all post 1933 and pre 1937.. I don’t know the correct order. 

3/8" drive extension

Model number

Description

Date Range

F-1

An extension 1 ½ inch

1933-1946

F-2

An extension (3 inch)

1929-1946

F-6

An extension (6 inch)

1927-1946

F-9

An extension (8 inch)

1933-1945

F-11

An extension (12 inch)

1929-1946

The FX series are the same with different heads

Model number

Description

Date range

FX-1

extension 1 ½

1950-1995

FX-2

Extension 3

1950-1978

FX-4

Extension 4 inch

1962-1978

FX-6

Extension 6

1950-1978

FX-8

Extension 8

1950-1970

FX-11

An extension (12 inch)

1948-1953

FX-18

Extension 18” long

1970-1995

FX-20

An extension (20 inch)

1935-1953

FX-24

Extension 23 ½

1960-1978

FX-36

Extension 36

1965-1995

Model number

Description

Date range

FXK-3

Extension 3 inch

1995

FXK-4

Extension 4 inch

1995

FXK-6

Extension 6 inch

1995

FXK-8

Extension 8 inch

1995

FXK-11

Extension 11 inch

1995

3/8” drive Flex Extension

Catalog drawings showing F-61 and FX-61 vs actual

3/8” drive Flex Extensions

I don’t have examples to look at, but the heads are obviously different

Snap on Model number

Description

Date Range

F-61

Flex extension

1941-1948

FX-61

Extension flexible  8”

1948-1978

FX-61A

Extension flexible  8”

1995

 

3/8" Drive F-61 and F-61A differences

3/8 Wobble extensions

3/8" Drive wobble extension set

A set of modern wobble extensions

These are wobble extensions and allow the socket to be driven from an angle.  These are modern, but interesting