Additional information:

GM used different widths, different weights and different timing positions, for a combination of seven different dampers, depending on what the engine is used for. The 350 used four different ones –
Part Number 6272221 is 6-¾”
Part Number 6272222 is an 8”
Part Number 3947708 is also an 8” referred to as “Special High Performance” and no longer carried by Chevrolet dealers (also used on the 302 motor).
Part Number 364709 is an 8” and specified for “Off Rod Racing”

GM trucks used a 7-1/4” OD damper for 265-350 trucks, 409 (trucks) an the 194-292 Inline-6 cylinder

305CI times at 12:00 o’clock position
350CI times at 1:30 o’clock

When in doubt – bring number 1 piston to TDC an install the correct timing pointer.