There were other sizes for the BB V6, I'm not shure of them but I do remember seeing somthing on a 350 BB V6. My grandfathers '67 GMC 3/4 ton 4X4 had a 305E V6 but it blew up in 1982 and a 350 was fit in but never finished really ( was drivin little in a feild but needed new bellhousing because of the size diffrence between motors ), the bellhousing was gotten but never installed, truck hasn't been run since 1983. I'd like to restore it someday.