I have just purchased a 70 manual R/T that was a 383,some where along the line it aquired a 440, the only numbers on this block are 2536430-6 which are casting numbers and a cast date of 13-3-67, it has no other numbers at all not even near the pan rail but up top we can only just make out D440 1130 or close to it,can any one work this out? it also has a aluminium bell housing would this be left over from the 383 with a smaller clutch and pressure plate? thanks for any help.