There was no block or content difference between the Braun and Lectron – MW era 3102 Demonstration Model.
The 3102 corresponds to the model 1102 but uses the 81mm x 81mm blocks. Instead of the standard meter block however, the 3102 model had a separating block for connection of existing measuring instruments like an oscilloscope or a very large analog meter which was sold separately. A loud speaker block was substituted for the two earphone blocks.
The layout from the original brochure: