year and model help

[White Shark]

I just bought a boat with twin 250 VX 76 Yamahas, the engines ID stickers are missing and on the side of the cowling there is a sticker on each engine that say: XYMXM313021B Engine family
the serial numbers are: G1BV2003497 & G1AV2011457
Can any one tell my what are the model no's or what year are the engines?

[boats.net]

None of those numbers match anything.