20 years working on Volvo construction equipment, so, no Dozer experience. I have seen some youtube videos, most no helpful. The steering clutch on the right is siezed. Lots of rust, found standing water in it, small cover left off. I removed all bolts on the pinion and sprocket sides, and brake assembly. the video shows it being lifted out after this, but I must be missing something because it will not just lift out. Serial number 79U1121.
there will be a small step on the flanges you will need to lever the assembly's so they are free. the brake hub should slide back over the clutch splines once it is un bolted