Maxxrickard, since you are using the FLM chassis and monoblock combo... your chassis will be the same length as mine... the drive train should be the same as well since your using the spider CD...
I don't see why you can't use the Savage XL center shafts... It's not a tight fit, so I used a little fuel tubing in each drive cup to reduce movement of shafts....
Did you drill the holes in the center skid to install the CD mount yet? if not... do a dry mock up with some dowels cut just over 142mm and 63mm... put them together and see if the fit will work
for you... if so, you will have a cheap fix to the drive shaft problem...
See the pic below:
If you look closely, you will see the small piece of fuel tubing in the cup apply outward pressure on the drive shaft
Alien