Clueless...
Well, since you disconnected the front wheel drive the problem is from the tranny back to the rear wheels (assuming the clutch bell is turning the spur gear).
Process of elimination will find the problem.
I think disconnecting the drive from the left front is unloading all the power. kind of like doing a 360 and the inside front tire comes off the ground and spins so hard it turns the tire into a pizza cutter. providing its an open diff and not a locked diff.
But…The 3.3 TMaxx is 4 wheel drive and if it is not moving there is an issue from the tranny back.
The TMaxx does not work like that ^^^^^^^^. It has a solid transmission output shaft and if power is being sent to it, equal power is then set to the front and rear of the output shaft. Disconnecting the front or rear diff by removing a center shaft, removing a wheel axle, stripping a wheel hex or breaking a hex pin (with an open diff) only eliminates front or rear wheel drive depending on where the disconnection is. The other diff being powered will still move the truck unless there is another disconnection.
The OP has eliminated front wheel drive by removing a wheel axle, still no movement with the truck on the ground. Other than the broken, then removed front wheel axle there is a problem somewhere from the slipper back to the rear wheels or the truck would still be driveable with rear wheel drive just like a SMaxx.
1<sup>st</sup> thing to look at would be your slipper clutch. Make sure it is working properly/tight and sending the engine power to the transmission. Also make sure the Clutch bell / spur gear mesh is correct.
2<sup>nd</sup> Check all wheel hexes, hex pins for broken pins or stripped hexes. Check the axles and center shaft grub screw pins make sure they are there and not broken.
3<sup>rd</sup> If the problem is still not found its time to open up the tranny and have a look inside for broken/stripped gears or pins.
The TMaxx does not work like that ^^^^^^^^. It has a solid transmission output shaft and if power is being sent to it, equal power is then set to the front and rear of the output shaft. Disconnecting the front or rear diff by removing a center shaft, removing a wheel axle, stripping a wheel hex or breaking a hex pin (with an open diff) only eliminates front or rear wheel drive depending on where the disconnection is. The other diff being powered will still move the truck unless there is another disconnection.
The OP has eliminated front wheel drive by removing a wheel axle, still no movement with the truck on the ground. Other than the broken, then removed front wheel axle there is a problem somewhere from the slipper back to the rear wheels or the truck would still be driveable with rear wheel drive just like a SMaxx.
1<sup>st</sup> thing to look at would be your slipper clutch. Make sure it is working properly/tight and sending the engine power to the transmission. Also make sure the Clutch bell / spur gear mesh is correct.
2<sup>nd</sup> Check all wheel hexes, hex pins for broken pins or stripped hexes. Check the axles and center shaft grub screw pins make sure they are there and not broken.
3<sup>rd</sup> If the problem is still not found its time to open up the tranny and have a look inside for broken/stripped gears or pins.