Re: Overdrive's for C4's
As much as I think that we would all love a 6 speed auto, from my reading of how these ones work, it would be a royal pain in the ass to drive. From what I read, you would start out in first and then engage the overdrive (for "first-over"), then change into second and at the same time disengage the overdrive (otherwise you'll go straight into "second-over"). Lots of changing gears and pushing buttons going on.
If your only looking for an overdrive, the AOD would definitely be the way to go, although they aren't necessarily cheap either (I was quoted $2400 for a fully rebuilt AOD with B&M clutch packs and all the necessary mods for a strong 351 - another $600 to fit it and setup the change patterns / kickback properly)