I don’t recall a write up on the -25 / XP coolant pump. Possibly. There were several posts a while back about the XPB and 35B coolant pump.
As I said I don't have access to my parts numbers but from the simple giggle search I suggested:
Coolant Kubota circulation pump for M-25 and XP
(CURRENT as of July 2019:)
Westerbeke
P/n 300203 (Universal)
price: $385.30
gasket p/n 300204
(
www.messicks.com)
Old P/n 15534-73030
Messick's Price $152.36
Stock Quantity 6
Replaced By 15534-73033
Replaces 15752-73032, 15752-73033, 15752-73030
Current p/n 15534-73033
Messick's Price $159.98
Stock Quantity 0
Days to Order 5-7 business days
Replaces 15534-73030
Gasket P/n 15676-73430
Kumar Bros (Amazon, eBay, etc.)
Kumarbrosusa.com
P/n. KBCO1003WP-D580
(D850 coolant pump)
$34.99
includes gasket & shipping