Volvo Penta got back to me about the difference between the earlier number 875697 and the 21651364. Both of them have the same impeller and the same gasket. The 875697 has an extra washer 827020 which you might not need anymore and 21951364 has a tube of grease.
So the attached quote means we can get the parts to you as soon as you wish (I picked 2nd day drop) and you will have to either throw in the grease or include it with the shipment out. Doing this means that you in effect get the part number 21651364 (with one extra washer).
Please let me know.