The numbers that are cast onto various parts are casting numbers not part numbers, and are in general not useful. It would be best to post pics of the parts you are talking about.

It would also help you greatly if you had both of the factory manuals ...
99451-78B Parts Catalog
99484-78 Service Manual

The parts catalog contains diagrams of all of the parts showing how they fit together and giving the correct part names and part numbers. The service manual has complete maintenance and service info.

You can buy these thru a local indie motorcycle shop or HD shop, or put the part numbers into the Google and eBay searches and buy on line.

 

if you have a parts book list the OEM part number of the ( KICK START SPINDLE THING ) and i will be able to help - correct parts names and or OEM part numbers is the only way to get the correct help --

almost everything in both those transmissions is the same and will work BUT always a but -- the trans door to trans door and or switching gears, shafts, becomes a thing with getting the correct end plays back so it will work again, can help - johnjzjz