at the top of the drive shaft below the splines? I changed my impeller and when I removed the lower unit there was no o-ring on the shaft. I did not see a groove where an o-ring would go either.The Seloc manual says "if used" place the o-ring at the top of the drive shaft. I did put molly lube over the splines upon reassembly and I'm just wanting to make sure that I did this the correct way. Thanks in advance for any advice.