Yes but the HD gearboxes are a different animal by all accounts. Hope Barrus will be helpful. Yellow penguin have a good relationship with their Rep. They managed to swing the thermostat dump valve replacement for me on my then 6 year old 275. Your boat is highly visible and well known in the area, good advertising for Merc if they help you with this. Also the one that broke was less than a year old anyway.
The gear ratio is slightly different on the HD lowers but rarely affects prop selection so hopefully you will be ok. Best of luck with the new gearboxes.