The size of the mount is identical to the one that came with the 3790. I panicked when I opened it thinking there was no difference and that I wasted my money, (or least the shipping to send it back); but There Is a Difference! Careful inspection inside the slotted speaker cover reveals an entirely different speaker assembly.
Performance is superior. Voices are now intelligible regardless of which one you choose, and I think, (imagine?), that there is even an increase in the volume without changing the Nuvi volume setting. This could be due to the fact that the voice output is less distorted. The Only time we had trouble hearing it was when we got into a hot car and the a/c came on full force. I highly recommend this product.