Skipping across the waves today my windshield shattered everywhere. After cleaning up most of that mess the drive wouldn't go into gear so I think my coupler is also shot. Anyone have suggestions on a VP DPS HD coupler part # or maybe a diesel version? Is the splines the the same as Merc?

What do you mean won't go into gear?? Does it shift at the shift lever and not move forward or reverse??

Yes, shifting the lever into forward or reverse does not engage the drive...

Usually if rubber lets go in coupler the boat will move at idle but not carry any more load than that. If the splines ripped out boat won’t move at all. You should be able to, with engine off, put drive in gear and have some one turn the prop while you watch the input shaft at rear of engine to see if it is turning, or trying to turn. I guess the drive is coming off either way, to replace coupler or repair drive.

If the splines have failed (been there, done that) the simplest way to determine it is to look at the rear of the engine while it's running and you'll see that the shaft to the outdrive is not spinning while the coupler is .

It was a coupler, just not the one I thought, The coupler between the upper & lower outdrive shaft sheered. If that's the weak link on this drive I can live with that.

Now you've got to figure out why that failed . They're designed to protect the internal lower unit parts by shearing if you should strike something with the props and it didn't sound like that happened , unless you ran over a part of the windscreen !

LOL, I don't think I hit anything. I do enjoy running it hard in rough water (fresh water lakes) so I think I must have twisted that coupler prior as I've ran it harder in the past. The motor is a low boost 509. I was reading the bravos have both aluminum & steel couplers/ sleeves so I wondered if there was a stronger version for the VP. I got another coupler from the dealer today & they said there was only one option which is steel.

Merc makes engine couplers in steel and aluminum. The Merc drive upper to lower couplers for the vertical shafts are all steel. I have never heard of one breaking in a Bravo drive. Its the shafts break most of the time.

aaah , so you got a big motor hooked up to that thing . That could explain a bit I guess. Interestingly Volvo only offers their 496 engine with the DPS/a drive and not the single prop SX/a unit. I think I read the explanation somewhere once but I can't remember what it was .
In Griff's message above I'm not sure about the upper to lower coupler he's referring to in the Bravo units but with the Volvos they're designed to fail if the props hit something. Kind of like an expensive version of a shear pin but still intended to spare a lot of expense.
To help put a bit of perspective on the incident do you know the power of the engine , size of the propset and the weight of the boat ?