If your current titanium Filter is a FWS-3003, then you do not need a nipple.
Titanium Series Note:
FASS has recently changed their Titanium pump filters from Fleetguard to Donaldson. All new Titanium Series Pumps include the new Donaldson filter FASS part number:FWS-3003. The Old Style FF-2003 will not fit the new pumps. If you have an old pump and want the new Donaldson Filter, you must purchase and install a new nipple for it. The nipple is an option below. You only have to buy it once.
If your current titanium filter is the FF-2003, then you need to purchase a nipple to use the FWS-3003.
NOTE: The original Blue Titanium models used a FS-2001 Water Separator. However, the newer Grey Series Titanium models use the same water separator as the HD models, the FS-2001. If you are unsure of which you have, the beginning serial number of the newer style is 26470, thus if your number is before that, you'll need the FS-2001, but if it's after that, you'll need the FS-1001.