I have a different clutch hub on my 750ltd. Help!

I just recently bought a new clutch pack for my 1980 750 ltd and was so excited when it came in. Then when I busted off cover and removed old ones. Come to find out the person before me, either upgraded the hub or just put something on there that fit. Anyways, my question is. I matched them up. the outside diamiter is the same, but inside the standard 750 clutch pack has a little smaller inside diamiter. I guess I am hoping it is an upgrade he did and if so would some one be able to tell me what clutch pack i mgiht need to get for upgraded hub or at least tell me how I can find out what hub he put on there. There are no part numbers or names of any kind on the hub its self. thanks for yall help or even time if no help can be given.

Weren't there two different 1980 KZ750's. I think that there was a twin and a four cylinder available in that year. My guess is that you got the twin clutch when you needed the four, or vice versa. I'm not an expert on 750's so this is just an observation.