Repaired leaking rear axle seals as described elsewhere, mounted new tires, tubes and rims, also described elsewhere, and decided now was the time to drain the transmission, hydraulics and differential.
Pulled the hydraulics (forward plug) first. The fluid appeared clean, a light golden brown. Next the transmission (middle plug). fluid discharged was darker and contained both a gritty sediment and a sort of sludge. I'm attaching a picture for reference.
Last was the differential, and it too had sludge; I pulled the plug and little water came out but nothing else until I poked my finger into the cavity, at which time sludge and oil came out.
I think the transmission and differential indicate (beside a lack of maintenance) the formation of deposits that Ford warned about in its specifications for trans /hydraulic oil. Certain additives were the concern.
My question here is simple: Should I give the cases a flush with some lighter-weight solvent, e.g. kerosene? What is the procedure for dealing with this problem?
Thanks for your suggestions.