4.3 l v6 omc buying new motor

[julianborrego3]

My 4.3 v6 omc (gm motor) got a crack on the block that is mixing water with oil, and i want to buy a new motor for my 1991 galaxie and i was told that i can buy it from the outparts store because is the same motor as the 1991 c1500 gm 4.3 l v6 z 262 and since i dont know nothing about it i want to be sure that i can do it and it will fit in my boat, can some one help me to understand this situation? thanks