I sure hope you don’t think you “fixed” it. There is OEM size which are typically the flat sided ones and there is oversized which are “splined” looking like you said . If the two sets “fell right in” you needed oversized and locktite doesn’t belong on ball joints .

You should of went with the ones that needed pressed in it doesn’t “stretch out your knuckle” it is supposed to be a very tight fit and need to be pressed in. By knurling the ball joint you increased the surface are which might get you by for a little while but when they fail you could have an accident and that could get you or someone else killed . I’ve had plenty of ball joint Replacements towed in to me to fix when someone put a ball joint in that didn’t fit correct and the wheel fall off and the wheel gets slammed up into the fender . Makes it a real PITA to pull off of the rollback . If I was you I’d pull those incorrect ball joints out and install the oversized like it needed . Moog part number is K3134T . Spicer doesn’t make an oversized joint for the XJ from my searching so use the Moog and If it still fits too loosely you’ll need a new axle housing ...