Type 9 front bearing

Hi,
For those who have reconditioned type 9 g/boxes:
 
The replacement ball bearing for the input shaft comes with a sheet metal shield on the inside! The bearing sits in the front of the case & the shield is on the oil side! It is a shield, not a seal & would let a little oil through to the balls & races, but at a greatly reduced rate. It is a Fag bearing & the packet is marked genuine Ford.
I have two type 9's with the same bearing, but without the shield. These were supposedly reconditioned boxes, but the front bearings haven't lasted long.
Perhaps the shield is there for some obscure reason, & should be left in place.
Has anyone built a box & left the shield in place, & how is it going?
 
Cheers, Gregg