glennj3,
I think your casting # is actually 348675. If so, that would decode as a 1973-79 250 CI rated at either 100 or 105 HP. That casting number does not specify what vehicle it would have been installed in.
The second casting info is the blocks casting "date code".
E145 decodes as:
E = May
14 = 14th day of May
5 = 1975
Note the "76" cast below the "GM" is an indicator it most likely would have been for a 1976 model vehicle.
Dan
