If the seals are just hardened from age, then new seals would take care of most of the problem, I suspect. There might be a chance that NAPA could find a kit via one of their vendors, if your local people know where to look, I suspect. Otherwise, one of the parts vendors (or contact several for hopefully a general consensus) might be a source for a reman steering box or provide a more-recently produced seal kit. Many of the external casting seals/o-rings might be replaceable with not much disassembly of the complete gear box unit. If you don't have one, a factory service manual might come in handy.