You need to be a bit more specific please. I am guessing the S37 has twin Volvo outdrives? If so, then the anodes will be mainly attached to the outdrives, so which outdrives? There will also be some on the engine coolant system. Which engines? Do you have a bowthruster? If yes, which one? Trim tabs will also probably need anodes. Sorry, more questions than answers.
The F37 Circa 1991 main hull anodes we used to look after had strange stud spacings for the two main twin stud mounted anodes on the hull, where Sealine got the anodes from was anyones guess?
The original anodes were also under sized in mass.
I think the ones we used were ZD 78 BM but the centres were wrong and we had to redrill the bolt centres in the steel plate and mill out clearance in the zinc for the sockets to secure the bolts.
If the boat is out of the water measure the stud size and spacing any small machine shop can modify them.
By far the cheapest anode supplier that I've found
You will need to select an anode yourself that fits - though.
BTW - this guy is from the "Old School"
He doesn't accept Credit Cards - you just order and he "trusts" you to send him payment AFTER he has supplied the goods.
I pay him by BACS
It is a real "breath of fresh air" finding someone who still trades like this.
I imagine that anyone not paying him won't get any further service and maybe those are so few that the saving in credit card fees outstrips this risk.