Thomson's or Grant's Gazelle?

This photo is from July 2017. I was pretty sure it was a Thomson's Gazelle, but it looks too big, and too leggy. Is it a Grant's Gazelle? I thought the dark horizontal stripe was indicative of its being a Thomson's - and I still would say that - but one or two things I have seen about Grant's seem to suggest that they, too, can have such a stripe.

I want to say that it's a thomson's... but I could be wrong.

This would be a Grant's Gazelle in my opinion. A good way to tell between the two is by looking for a white patch on the rump. In this picture the white patch comes up over onto the back flank which is indicative of a Grant's Gazelle. Thomson's do not have that and the white just continues to arch under the tail, so to speak, and over the rump. Horns are a different shape, typically, as well. Size is a big give away as well. Because of the subspecies of both, the stripes are bad Identifiers. This is the extent of my knowledge and my best swing at identification.

This is indeed a grant's gazelle, but a young one to make it difficult , the proportions are not completely right for a Thomson's (relatively long legs and neck) and the white of that continues above the black stripe is also a give-away.