The Stovebolt Site Forums The Shop Area Driveline 1951 3600 Front Prop Shaft Oil Seal

This might help.
Here is Denny Graham's 1950 3600 front torque tube rebuild photo album.
https://pbase.com/dennygraham/driveline&page=all

Also 3/4 ton truck propeller shafts in 1948-1951 Chevrolet Truck Shop Manual
http://chevy.oldcarmanualproject.com/shop/1948_51truck/51ctsm0452.htm

1929 - 1954 Master Parts and Accessories Catalog illustration
http://chevy.oldcarmanualproject.com/parts/1929_54/339.htm

I'm not sure if the sleeve is the original fitment.
But I can't see how the oil seal could damage the propeller shaft.
The rear bearing and the front bushing keeps the propeller shaft centered in the torque tube housing.
Is the sleeve machined into the shaft or does it look like it is pressed onto the shaft?

1929 - 1957 Master Parts and Accessories Catalog
Group number 5.433, Seal
41-53, 3/4 ton, front propeller shaft bearing (Seal), part # 3689176+
+Note: Use with propeller shaft machined part length and with bearing Seal Sleeve pressed on.
http://chevy.oldcarmanualproject.com/1929_57chevyparts/57cmpc0477.htm
Looks like the sleeve is an original fitment and is pressed on.

Someone may come along that knows for sure.

xfiles