489 pinion bearing install?

Is the front pinion bearing cone supposed to be a slip fit over the pinion shaft on a 489 case, or does it have to be pressed?

I'm setting up a TrueTrac w/ 3.23s, and trying to set pinion depth. The problem is that the front bearing won't go down over the pinion shaft. I've tried this with two Timken bearing sets, and two different OEM 489 pinions.

I've set up a 742 before, and the front bearing was a slip fit, so this has me scratching my head. Any hints on how to proceed would be really appreciated.

Thanks,
PH