megaladon6 said:2 posibilities, a 350ci motor with a 400 trans. or a buick 350--if i remember correctly some BOP blocks from 350 up to maybe 455 were identical. the factory just put in a different crank/stroke. either that or the 350 shared the exterior dimensions with the larger blocks.
to be positive we need casting numbers and maybe pics.
he's selling the transmission with the motor because he told me my transmission woul'nt fit...Maybe your first option is good