During the years before 1948 the Rock-ola Manufacturing Company used locks from two different companies - Bell Lock of Chicago and EPCO (The Electrical Products Company division of the Eagle Lock Company).  The 5/8 inch locks were used both as coin box locks and wall box locks which attached to metal.  The longer 7/8, 9/8 and 11/8 inch locks were used on door or cabinet locations mounted on wood.

The Rock-ola key codes are largely a mystery to me.  There is a wide variety of one and two digit numbers ranging from 1 to 63 that precede the RO and I believe they mean something unknown to me.   I now believe the 60 and 61 series are post-war and are for the 1422 and that the 62 and 63 series are for the 1426 and/or 1428.  I have not yet seen any of these post war keys that have the Rock-ola name embossed on the reverse side as many of the earlier series keys are.  At one time I thought the numbers following the RO just meant one more key in that series until I realized that 616 and 620 were being used on top  lids and front and back doors on 1938 to 1940 models, or that almost all of the 616 keys - no matter the first number - are identical.  Same goes for the 620 keys. 

Please message me if you can shed any light on this mystery.

The lock offered here is from the 27 RO series which I believe date from 1939 and/or 1940.
The distance from the inside edge of the front to the face of the cam is about 5/8 of one inch.

This is a good lock that works well with the original key that is included.