A noon trip to Theisens (local farm supply chain) produced a quite heavy duty ratchet jack. However, it uses square threads, completely different than the threads of the toplink or any top link they had on sale there. So, for now, I passed. A simple solution would be to buy weldable link ends, which they have, and simply cut off the crosspin yokes on the jack and weld on the ball-end links. But I'll have to pay someone for that. I'll poke around in a few other places first. Meanwhile, think I"ll go home and eyeball my tractor for potential to fit with an 8N side link leveling device.