#3734908
The Part number 3734908 is a Bellhousing cover
that is called an extension in the parts catalogs.
This inspection plate is used in conjunction with
part number 3704923 underpan to reduce the amount
of road grime entering the clutch housing, and to
guard against stray fingers and animals from getting
caught in the rotating clutch assembly.

New OEM Part # 3734908
Pictures and descriptions come from a new unused
replacement part. This is the upper component of
the two piece gravel guard used on early (1955-197?)
clutch housings.

Inside
The "bump" on this shield (left end in above picture
Will hang extend past the driver side of most car
bellhousings and may need trimmed. The large
hole is for the starter.
The three holes around the starter hole are for
starter mounting as the clutch housings this
component is intended for, have the starter mounted
to the housing not the engine. This shield may or
may not need trimmed in this area for engine
mounted starters

Part # 3734908
This view shows the part number tag one of the
two (2) cover mounting thru holes and the "bump".

On "505" Bellhousing
Here the "908" inspection plate is shown on a
part number 3925505 clutch housing. In this
application the "bump" is needed for full coverage.
Also in this picture you can see the two (2) shield
mounting holes.
that is called an extension in the parts catalogs.
This inspection plate is used in conjunction with
part number 3704923 underpan to reduce the amount
of road grime entering the clutch housing, and to
guard against stray fingers and animals from getting
caught in the rotating clutch assembly.
New OEM Part # 3734908
Pictures and descriptions come from a new unused
replacement part. This is the upper component of
the two piece gravel guard used on early (1955-197?)
clutch housings.
Inside
The "bump" on this shield (left end in above picture
Will hang extend past the driver side of most car
bellhousings and may need trimmed. The large
hole is for the starter.
The three holes around the starter hole are for
starter mounting as the clutch housings this
component is intended for, have the starter mounted
to the housing not the engine. This shield may or
may not need trimmed in this area for engine
mounted starters
Part # 3734908
This view shows the part number tag one of the
two (2) cover mounting thru holes and the "bump".
On "505" Bellhousing
Here the "908" inspection plate is shown on a
part number 3925505 clutch housing. In this
application the "bump" is needed for full coverage.
Also in this picture you can see the two (2) shield
mounting holes.
Applications
3734908
0.679 EXTENSION, Clutch Housing
55-62 Y (8 cyl.) (NOTE 1)
NOTE 1 : Has two indented throughs on surface, trim excess metal as necessary
55-62 Pass. (8 Cyl.) (exc. 409)
55-62 ALL (265, 283) (Truck)
63-67 Ser. 10 thru 30 (283) (exc. A.T.) (Truck)
63-72 Ser. 10 thru 30 (292) (exc. A.T.) (Truck)
63-69 ALL (194, 230) (exc. A.T.) (Truck)
68-70 Ser. 10 thru 30 (396) (exc. A.T.) (Truck)
69-72 ALL, Blazer (250, 350) (exc. A.T.) (Truck)
65-72 Ser. 10 thru 30 (307, 327) (exc. A.T.) (Truck)
Disclaimer:
Factory correct applications are your responsibility. GM made part and part # changes with no rhyme but a reason (no production interruptions at any cost).
Application charts and part numbers are for replacement parts that were available at the time of parts book printing.
My observations come from the parts I have in my collection or other reliable sources your parts may differ.
If Factory correctness is your goal, do more research, join car clubs,
forums and buy an assembly manual if one is available for your Project Car (you won’t be sorry).
This is a fun and interesting part of the hobby!