That part also tells that there's a difference:
3104 Frame 5-3/4 x 2-1/4 x 9/64, 2.46 cu in Section Modulus (a measure of stiffness)
3604 Frame 5-27/32 x 2-1/4 x 3/16, 3.25 cu in section modulus
So the 3600 frame is a touch deeper as well as a bit thicker, which makes it stiffer. If other critical dimensions are the same, that depth dimension difference (3/32") wouldn't make that much difference in mounting an IFS kit. I would think it would increase the ride height by that miniscule amount.
