Hi guys, I have joined up here to learn more about what this market needs/wants.
I have been reading this thread and was thinking about developing a front driven axle for the Semi/Tractor trucks. I did a little bit of testing with an axle that has been on the market for a while and found that it may already meet your needs.
The RC4WD D35 front axle is 2mm narrower than a TLT axle. The axle comes with a spool fitted that is the ratio as the Tamiya diff but the axle is fully compatible with the TLT/High Lift/Semi truck diff. It is basically a scale looking TLT/High Lift axle that has been narrowed slightly and the diff has been offset to one side.
http://store.rc4wd.com/D35-Front-Sca...xle_p_463.html
Here are some pics I took of this axle with stock Tamiya inside rear wheels fitted. With 6mm thick hexes fitted you can see that the track width is only about 1mm wider.
5mm thick hexes will bring the wheel in a little more. The leaf perches are on top of the axle but the axle could be flipped to mount the leafs at the bottom.
So does this axle meet your front driven axle needs?