The last of the B models were actually C models with different fenders. They moved production to a new plant and stuck the B on for the first few months. It can be a pain to get parts, especially when the dealer orders parts for an early B after being told a late B.
They have enough hydraulic capacity to lift a lot more than they should be lifting. And they are great in mud, having the taller narrower tires, and an extenda-a-hoe. You can balance them on the rear tires and walk right through stuff that would have a 580SM getting chained to the dozer. 4X4 front tires are a bit of an oddball size, but with that tall sidewall you won't blow beads over the side of the rims, or bend rims, like you will with the Case machines.
They are fairly simple machines, but tearing them apart is not fun. They start with this piece, add this one, then this one, then this one, and to get to anything, you have to tear it ALL back off.
If the transmissions slips chances are it's a couple o-rings. But to get to them, you need to pull the loader, front bolster and axle, and motor, to get to them.