xxibishn

I have a 56 holiday 88 but from what i was told the engine is from a 61 year olds. the casting numbers i have found are on the rear of the block on the bell housing they are as follows "578135-4 1/8" i have no idea what the "1/8" is or if this is the correct place i am to find the casting numbers, i have looked all over block and nothing