I'm peparing to complete my M4A3E2 and realized that I don't know the make up of the treads in order to highlight them correctly. Is it correct that they are mostly rubber with metal connectors and, in this case (M4A3E2), metal feet extenders? Just to be sure, so while German treads are all metal (right?) and therefore I can use metallic colors for the base and various highlights, for the Sherman tread they should be mostly black/rubber in color with detail metallic highlights in between each tread?

What do the tracks look like?

Sherman tracks could have either rubber or steel blocks, but the connecters and 'duckbills' were always metal.

This article should help you identify your tracks

http://web.inter.nl.net/users/spoelstra/g104/track_vvss.htm

Basically, rubber blocks have much wider chevrons moulded into them.

All Sherman VVSS tracks have a rubber inner and I believe the uppers too. Some of the cleats were also rubber or flat rubber block (and the waffle track which was only used on the Ram I believe) but most cleats were metal. As Drader said the rubber chevron was much wider, noticeable wider than the metal. The metal chevron was very narrow. The end connectors and duckbills are all metal, no metal in between the tracks. An M4A3E2 would definitely have the duckbills this was do to the increased wait of the extra armor.

The tracks listed on the Sherman Register site as "Rubber" used a solid rubber block molded around steel pins; those listed as "Steel" used a steel block or two steel half-blocks assembled around rubber bushed pins; and those listed as "Steel tread and rubber top links" had steel blocks with rubber molded on the inside (wheel) faces assembled around rubber bushed pins.

The all steel tracks wore the bogie skids rapidly, which lead to the raising of the return roller.

KL