That model is essentially unchanged from the 9400 that preceded it by a few years. At that point they were offering two 4" machinist models...standard and HD. The HD model used a larger diameter spindle, opened wider, and weighed several pounds more.
There is a discussion of them in another thread I'll try to find. On a swivel base that version weighs right at 55lbs as I recall. Side by side I couldn't see any difference between that and one just like it that was marked 9400 (had both at the same time).