The FH36B is very similar to the current FH36H. The only real difference is that the H has a faceted shape at the top of the soundbox, making it a bit more comfortable where it rests on your shoulder. We call it the hybrid staveback. The B has a rectangular body all the way to the top. Otherwise, they are virtually the same. I think it's been about 8 years since we switched form the B to the H.
That particular harp was built in 1998, which means it also has tapered tuning pins and round bridge pins instead of our current threaded pins. The threaded tuning pins are a bit easier to use since they don't tend to work themselves loose and need to be re-seated, and the threaded bridge pins make it easier to regulate your harp, but it's really not a big deal to have the old-style pins.