Wow, what a response guys!
@Typpo: That amount of info on the Kyosho CVDs is very interesting, thanks for sharing!
I will do some comparison work in Photoshop between different pictures and what shows potential will be sourced.
I did find a slightly better option in the meantime than the Tamiya CVDs, being Tamiya's Universal Shaft wheel axles (not WO Universal/CVD) with the 65mm Durango DEX210 bones. It fits as if Durango copied the geometry of Tamiya's U-joints
Ok, Tamiya's '64mm' shafts actually seem to be 64.5mm, so I only gain 1mm of width, but it is still 1mm wider, plus, the outdrive pins now have the perfect diameter.
Nonetheless, my search continues. There is room for improvement, hence no reason to stop searching!
PS: I'll also share the pictures of the Xray XB4 vs. Tamiya 201 CVDs to show you why the Xray axles are interesting and the bones are not suitable for my project.
@optiman: Nice B44 truck! My guess is that that car too will have some acceleration issues with only front wheel drive, but it's an easy and fun test
Every time a 4WD buggy's drive on the rear breaks down I'm closely monitoring how it gets around the track, and to be honest for something that just happens on the spot they do pretty well
@smokes: A double cardan shaft may work very well - in fact, there are so many 'constant velocity' solutions out there that are interesting to have a look at... I'd love to make a Rzeppa joint for an RC car (the one in the center):
This does require too much customizing or even machining from scratch. Even the D-joint from Durango is a bit complicated to work with for now, but these things are worth thinking about (especially the double cardan joint because the availability of the D-joint or putting two CVD systems together)