yiela,
Yes and No..
You can convert the current truck into crawler.. but, to do this, you need to have some fab skill...
For crawling, independent arm is not the choice. We normally go for those solid axle like the TLT and Clod or AX10 Scorpion.
Also, the differential effect is not desired or required at all. Most will go for "locked" diff.
As for the
1. Hex is 17mm - you need to convert it to accept 12mm so you can mount the beadlock wheels or depending on the type of wheel you want to use.
2. Motor Mount - Again, this will need some creativity and some fabrication skills. You have to fabricate a gearbox where you also mount the motor. The gearbox must have output drive to feef the drive shaft to your axle.
3.Center DIff? - Not really a diff, but a locked gearbox / or gear reduction.. again, some creativity and fabrication skill.
If you really want to go into crawler, with minimal spending, assuming you already have the servo (high torque), esc with reverse and transmitter, go for the AX10.
What I mean with minimal spending is, the kit is basically crawler ready where the diff is locked and the gearbox is also locked. All you need is the electronics. I wouldn't go for the RTR version though...
just my opinion... hope this helps....
cheers...