I have a IO-360-A1B6D engine (from a Mooney 201) in my RV6. I have an single Electroair electronic ignition that uses a flywheel sensor for crank position. For the magneto side I have a single mag that was adapted for use on the single drive dual magneto case. I have read some posts from folks looking for information on single mag options for this style accessory case. I just had my mag overhauled so I thought I would share what I learned from the shop. My mag is lableled a Bendix P/N 10-51360-12, but it has been modified so don't go out and get this part number and expect it to bolt right in! The single drive case uses a drive that is somewhat unique in the four cylinder Lycomings. Rather than a gear like I have seen on my other mags this one as a flat raised bar (or key if you will) that interfaces with a slot in the accessory case. This drive setup is super easy to install as it is not really possible to miss a tooth on the gear and end up in the wrong place. So if you what a single mag to run on your single drive dual mag accessory case you need to find a mag shop that can graft an appropriate single magneto to the single drive dual mag drive configuration. My shop told me my mag is basically an Continental 0-200 mag tied to a drive from a single drive dual mag drive. So it certainly is possible to get one built up if you want the smaller form factor. Just FYI!!! Happy Flying