Which Engine? Which Intake?

D4B is the manifold for the original ('64/'65) 273 with the "odd" intake bolt angle.
LD4B is the later ('66 and up) manifold for the now-standard bolt angle.
Both are identical otherwise, small port (273/318) runner size.
Since it has an LD4B on it, your engine is a '66 and up motor, or an earlier block with '66 and up heads.
To know what the block is, look for the casting numbers on the driver's side of the block for the displacement, and on the passenger side for the casting date.