Hobby Boss has released a 1/35 t-35. Also they produce a set of t-35 tracks as a separate product.
Will the t-35 tracks from this separate product also fit the t-28?

The T-28 and T-35 were completely different vehicles, so I'm not quite sure why you might think that the tracks would be interchangable. Sure, they shared a few of the same components, but that is it. T-28 tracks were 380mm wide with a 170mm pitch, T-35 tracks were significantly wider at 526mm with a pitch of 160mm.

As for the Hobbyboss kits, I'm also unsure why you might want to use the T-35 tracks. The T-28 kit(s) already come with non-workable individual link tracks, whereas the T-35 kit(s) come with link-and-length, which is why HB has released the separate individual link track set.

HTH
Jon

Thanks Jon. That's what I needed to know! Thank you for responding so quickly.