What were the "Duckbill" track connectors used for? A wider footprint for soft ground/amphibious landing? Would they have been left on very long and would you have seen a lot of them in D-Day operations?

Duckbill track extenders were developed during the Fall/Winter of 1944-45. The major allied armoured units in Europe were having problems with the mud from the Autumn rains and eventually the snow. They were used both in NW Europe and in Italy, right up to almost the end of the war but certainly not for D-Day.

They came in many different configurations. As Steve Zaloga put it:

"The reason there was no standardization of duck-bill parts numbers was that a large portion of the duckbill EECs used in Europe in fall 1944-winter 1945 were locally produced in Europe. The Army was so desparate for these due to the muddy weather that they put out local contracts in France and Belgium to have duckbills locally manufactured.This was the reason for all the variation in detail and design."

Check out: http://web.inter.nl.net/users/spoelstra/g104/track_vvss_con.htm for more details.

As nemanja stated they were not used on D-Day as they were a field modification occuring later, to combat muddy bogged terrain... Seen many pics of bogged Shermans WITH these in place, as often they were nullified by the additional weight of sandbags, or poured concrete reinforcement etc.
Is this for an upcoming build? Would the question be are you building a tank at the landings, or one that has end connectors? Many of these broke off, and I have yet to see a pic of a Sherman with a complete set after re-entering combat...
Heavier tanks like the M4A3E2 'Jumbo' were manufactured with permanent duckbills for the added floatation over marshy ground...
Anything in France from September onwards would have meant heavy rains rom what I've discovered
HTH
Cheers and HNY
*clink*
Brad