Stop in for a cup of coffee
Yes, the LD340 is made for the large port 340/360 heads and has the coil mount bosses in the stock position...
The LD4B is made to match the smaller 273/318 ports (66 and later bolt pattern) and does not have mounting bosses for the stock coil position. You must relocate the coil to use this one...
The D4B is made for the small port 64-65 273 heads with the smaller 5/16" intake bolts at the different angle than the 66 and later intakes. I'm not sure about the coil bosses on this one....
All good intakes for a small block. Either will run well on the small block, even if the ports are not "matched"....