In the "Classic Ballon Tire ..." forum there is a thread titled the 'Murray Serial Number Project" in which there are lists and comments that will help you identify your bike. The thread is not pinned so youll have to scroll down to find it. The last post was made around the first of June.
In your serial numbers, the MOD 502 indicates the bike is a JC Higgins / Sears ( not sure which year the name was changed to Sears.)
The MOS is for Murray of Ohio Supply and the U will identify the year. The 4544X will tell you the model. Once you figure out the year, find a Sears catalog and look at the catalog number that matches. That number was used for sales, parts, and service,
Looks to be MOS-U, which I have as 1955. From what I've seen, JC Higgins didn't offer a full, flashy deluxe model in 1955. It could have been due, in part, to the strikes at the Murray factory which caused much of the manufacturing year to be outsourced to Austria.
1954 was the last year the Colorflow was offered, and 1956 introduced the Jetflow. So I think this may have been the most deluxe available for '55. They possibly offered it with a light and springer, though. Can anybody confirm this? I can't locate a 1955 Sears catalog to check.
1955 Spring and Summer catalog; model # 4544 looks to be the top one, similar to fully equipped - for that year, but with De luxe accessories. What a difference a year makes (on paper) for accessories, chainguard, light, rack, tank.