1969 rear axle tube code

[bvb69C10]

I bought a 69 c10 recently that has parts on it from other years like the 70-71 tilt steering column. that being said, I've read some of the forum discussions on rear axle codes and the code I found on the passengers side axle tube doesn't match anything I've read. This is what is on the axle, 145SWAHR or B if not R. It's on the top of the tube so I'm reading it with a mirror but I don't think I got it backwards. I'm starting to wonder what else had the same wheel base as the truck at this point. Any help would be appreciated.
Thanks