I am looking for a replacement HBW10, do you have any in stock?

 he HBW10 is the same as the ZF 10M.   However ZF Marine no longer makes the ZF 10M and instead
has sold the ZF10M manufacturing rights to another company in Italy.   So I can supply you with a ZF
10M, but it is expensive.

It is better to swap over to the ZF12M which is a stronger gear and is still made by ZF Marine.
It is about .5 inches longer so you do  have to adjust your engine or your prop shaft a bit.  Most
people find they have enough play in their shaft to adjust for the slightly larger gear.