OK, see that's my confusion with the sizes, hence my hesitation to say them exactly.
I know for a fact that the 1st Gen Sequoia and 2nd Gen Rav4 stereos are too large to fit the 3rd Gen 4Runner, and that there's an 'ear bracket kit' to fit smaller double-DINS (like the 3rd Gen 4Runner's) in those cars. I believe the 4th Gen 4Runner takes the exact same larger stereo.
But I've seen some aftermarket stereos fit flush in those too, so there's obviously a wider standard size available.
I guess the main confusion is that aftermarket stereos apparently often aren't completely accurate in their size listings, most especially when you get a Chinese 'eBay special'.
May or may not fit, just buy what you like and hope they have a good return policy if it doesn't fit.