im late to this but an hx35 and hx40 have the same size shaft. they are rebuilt with the same rebuild kits. hx30,35,and 40's are all the same. the difference is the wheel size. an hx40 has a 65mm turbine and a 60mm compressor. this buts more stress on the already small shaft. they work but fail often because of there small shafts. ans s300 base turbo is a stronger better upgrade all the way around. it is much more expensive but its a better turbo. and ide be in the 62/65/14 range on a charger for you.

 

It doesn't really matter which series you have, 35 or 40 if your turbo is barking, you have a ticking bomb.