Under the first case, 148-6136 is often called a belly number but it can also be referred to as a confidential number, a crankcase production number or a line-bore number. Is the same number under the damaged case?
First 1 is a code number and it was used for 1948 model Panheads regardless of engine size (61ci and 74ci).
Next two characters (48) indicate model year.
Last four characters represent sequential machining production. (For 1948 models the sequence numbers began at 1000.)
Inside the case is casting number 112Ė48.
K 7 is a date code indicating the case was cast in November 1947. (Notice the K appears incomplete but Iíve seen several like that.)

Inside the other case is casting number 24541 55.
The circled E is a casting hallmark. It represents Eck Industries, Manitowoc, WI, according to Bruce Palmerís 37Ė64 restoration book.
Itís hard to be sure about the date code. What is it?
Is there a belly number underneath the case?