There is someone over here in the Netherlands selling a pair of woofers for (some) Reference 3A speakers, but, mainly due to the complicated history and line up of the models before the current series, it's hard to determine if these would fit the cabinets. FWIW, it's the woofer with the squarish surround of the basket, while the cones are made from some yellow material in a woven structure. If you are interested in the woofers, or info on that matter, I could try to contact the seller.
Hans