Scott A46A Secret Mark?

Is this the extra shading of the secret mark for this stamp? It appears to be not re-engraved. Making it a Scott 158 or 184. I used the "Large Bank Note Identification" page on Bill Weiss' site.
I guess I'm using you folks as a checks and balance in my learning curve. Thanks.

Looks like either 158 or 184 to me too.

The cancel dates it to 1878-1882 or so (I'm too lazy to go and grab my copy of Blake-Davis). That's a Boston cancellation. I have a collection of those.

The easiest way to tell a 158 from a 183 is to check the paper, if it's mottled it's soft paper and hence a 183.

Excellent. Looks like I got the markings correct. The back of the stamp is a mess so telling the paper would be difficult.

Hold it up to good light, unless it's been completely rebacked part of the original paper should be visible. Soft paper looks almost like a mesh under good light.

Seeing the date range of those cancels I'd lean towards it being a 183.

183? Wrong denomination and color for that. I don't see many fibers protruding from the perf tips, and the shade of the design has more yellow in it than American typically used, but I would not hazard an opinion on this one without seeing the actual stamp. I lean toward a 158, or possibly Continental intermediate paper. Online images are notoriously poor for making paper discriminations. Show us an image with transillumination and maybe then we can say more if there isn't too much interference from the stuff on the back.

&^%$*&^%ing iPad.

184.

Looks like that cancel was known to be used late in 1877, it's a 158 based on that.

Thanks folks. billw2 I knew you meant 184 lol. essayk, I think I would need to soak it to remove remnants to have a better look at the back. The parts of the back that do show are thinned. This was excellent for me and the 'special mark' of this issue. Thank you.