Maybe this can help...
BBC Engine Block Casting Numbers Casting # Year CID Comments 340220 1972-76 427 tall truck 345014 1974-86 454 truck 346236 1974-76 454 215, 2 bolt 359070 1974-90 454 truck 361959 1973-85 454 car & truck 364776 1968-84 427 tall truck 364779 1968-88 366 tall truck 473478 1968-84 427 tall truck 3782870 1968-76 427 tall truck 3855061 1965-67 396 3855961 1966-67 396 325, 360, 2 bolt 3855962 1965-66 396 360, 375, 425, 4 bolt 3855977 1965-67 366 tall truck 3866961 1966-69 396 Chevy, Chevy truck 3869942 1966-67 427 390, 425, 2&4 bolt 3873858 1966 396 375, 4 bolt 3902406 1967 396 325, 350, 375, 2&4 bolt 3902466 1965-67 396 ?? 3904351 1967 427 385, 390, 400, 425, 430, 435, 2&4 bolt 3904354 1966-67 366 tall truck 3916319 1968-85 366 tall truck 3916321 1968 427 385, 390, 400, 425, 430, 435, 2&4 bolt 3916323 1968 396 325, 350, 375, 2&4 bolt 3918319 1966-70 366 Chevy truck, GMC, tall truck 3925521 1968-85 366 tall truck 3928319 1969-73 366 GMC, tall truck 3935439 1968-69 427 335, 390, 400, 425, 430, 435, 2&4 bolt 3935440 1968-69 396 265, 325, 350, 375, 2&4 bolt 3937724 1968-85 366 tall truck 3937726 1968-84 427 tall truck 3955270 1969 427 335, 390, 400, 425, 430, 435, 2&4 bolt 3946052 1969 427 430 ZL-1, 4 bolt, aluminum 3955272 1969 396/402 265, 325, 350, 375, 2&4 bolt 3955274 1968-85 366 tall truck 3955276 1968-84 427 tall truck 3963512 1969-71 427 335, 390, 400, 425 COPO, 430, 435, 454 345, 360, 365, 390, 425, 450 2&4 bolt 3963513 1973-76 454 215 3965440 1968-69 396 3965449 1968-72 396 3965540 1968 396 3969854 1969-72 396/402 240, 265, 300, 325, 330, 350, 375, 454 360, 2&4 bolt 3969858 1968-84 427 tall truck 3999289 1972-78 454 215, 235, 240, 270, 2 bolt, car & truck 3999290 1972 402 240, 2 bolt 3999293 1968-85 366 tall truck 3999294 1968-84 427 tall truck 6272176 1968-76 366 Chevy, GMC, tall truck 6272177 1972 402 210 6272181 1973-76 427 tall truck 1401544 1975-87 454 truck