Nevada Club Jennings Question

[5 cent player]

I have a question, I have noticed on some of these Nevada Club jennings that the there are a few differences from the normal sun chief's. Some do not have a serial number on the side of the case, some have no serial number on the mechanism and some also have back doors that do no not have the ODJ letters, but instead have just the J. Is this normal? Did the Nevada Club make these parts in house? I know they made and replaced some part inside. What are your thoughts? Enclosed is a link to a current machine on Ebay for an example, its not mine. I asked this seller these questions and he did not know. Thanks in advance.

10 cent Nevada Club Jennings Slot Machine Sun Chief #200898084200

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... TQ:US:1123