I'm looking for a conversion box for an older GM vehicle with mechanical speedometer. Don't want to go the aftermarket gauge route, trying to keep stock appearance. While I would love to try and DIY something I don't have the extra time. There's Cable-X that's been around for sometime. I've heard that they are loud, and would like to keep mine hidden under the dash.

Now there seems to be 2 relative new comers, Dakota Digital's ECD-200BT and Speedhut's Speedbox. I have found one video of the ECD-200BT and it seemed noisey. The video and reviews I've read about the Speedbox is it's quiet. It also has GPS driven speed, which I don't really care much about, but it is a nice feature I guess. Both are relatively the same size.

Has anyone used either of these or both and can share their experience/recommendation?