No less than five speedometers were used in Chevrolet trucks during the Advance Design years, 1947-1955. If you want your truck just right, be sure you understand the differences. Restoring one you have on a shelf or purchased at a swap meet may not be proper for your year. The following will provide a description of differences.
1947 speedometer

1947

Red-Orange needle. Lower two tabs 4 3/4" apart. 80 MPH (A clear needle means the color has faded away.)

1947 speedometer

1948

Red-Orange needle. Lower two tabs 6" apart. 80 MPH

1947 speedometer

1949-1951

White needle, lower two tabs 6" apart. 80 MPH

1947 speedometer

1952-1953

White needle, lower two tabs 6" apart. 90 MPH

1947 speedometer

1954-1955

Totally different from earlier years. Silver needle over black face. Few parts interchange

Then there is the GMC speedometers used during 1947-1955 (Only 1952-1953 are the same.) That is another story!