Can your gearbox be rebuilt? The one on my D12 rehab had lost the bearing balls on the worm gear shaft, the outer seal on the output shaft and the seal on the steering column. I was able to match up the bearing balls from #605 sealed bearings (busted open the sealed bearings to obtain the balls). The ball races may be able to be matched up with other manufatures ball races, mine were usable, so did not research replacements. The output shaft seal is still available from AGCO. A friend (with a small lathe) turned a new steering column bushing out of FRP plastic for me. Made my own cover gasket out of gasket sheet stock and small ballpeen hammer.