Fd620d engine and clutch questions

Hello everyone. I have an older 6x4 gator serial number 148xx which I believe to be 96 or 97. I bought it as a project and the engine was out of it. It came with what I thought was the original engine but I now have my doubts. Clutches were missing and I have them on the way but l looked at the crankshaft output shaft and it is splined and not tapered like the ones I see on eBay for the gator. I will post a pic later. My question is we're the early ones different? If not are the fd620 kawasakis all the same if I switch the crankshaft?

Thanks in advance.