Hy Josh_51GMC, you could use 80-90 wt. for all three of those applications, after you fill watch for leaks from everything. The transmission fills through a plug on the side of the case. about a third of the way up the side, fill to the bottom of the threads. The diff. fills through a plug in the rear of the housing (actually a cover), fill to the bottom of the threads. The steering box fills through a plug in the top of the housing, there has been a lot of discussion about using John Deere corn head grease in the steering box as it is obviously less likely to leak out, hope that helps.
