Fleetguard 142784S filter base comes in 1/2 NPT and ORB. Cummins dealer quoted $19. 00 in Minnesota. See other filters, bases/heads below. WIX also has a head for $15 on fleetfilter.com under miscellaneous. Nice if you want to mount to vertical surface.
I copied the following from "Biodiesel and SVO Discussion Forums" by member Ziptar
I use Caterpilar Filters # 1R-0749 and # 1R-0750 on my Perma cool heads, they filter down to 2 micron.
This Help??, it isn't an X-ref for the Permacool Filters but it's an X-ref for the CAT filters that worls on them??
Cat Filter X-ref
Caterpillar Primary Filter/Water Separator 175-2949 (threads 1-14 UNS-2B )
Fleetguard FS19683
Donaldson P551743
Baldwin BF1268
Wix 33005
Luber-Finer LFF8030
ACDelco TP1002
Caterpillar Secondary Filter 1R-0749 (2 Microns) (threads 1-14 UNS-2B )
Fleetguard FF5319
Donaldson P551311
Baldwin BF7587 (BF614, Standard Version, BF7633, Short Version)
Wix 33674
Luber-Finer LFF2749 (High efficiency version of LFF5823B)
ACDelco TP1322
Fram P8335
Purolator F75185
Hastings FF1056 (FF1007, Standard Version FF1079, Short Version))
Caterpillar Filter 1R-0750 (2 micron) (threads 1-14 UNS-2B )
Fleetguard FF5320
Donaldson P551313
Baldwin BF7633 (BF7587, Long Version)
Wix 33528
Luber-Finer LFF3347
ACDelco TP1326
Fram P8334
Purolator F65213
Hastings FF1079 (FF1056, Long Version)
Filter Heads (1-14" Thread)
Perma-Cool 88864 High Flow Filter Head (1/2 NPT Inlet / Outlet)
Perma-Cool 81074 Fuel Filter/Water Separator Kit (1/2 NPT Inlet / Outlet)
Perma-Cool 81794 High Performance Filter Head (3/4" NPT Inlet / Outlet)
Fleetgaurd 142784S (1/2 NPT Inlet / Outlet)
Donaldson P174768 (7/8-14UNF)
Baldwin FB1311 (7/8-14 UNF Inlet / Outlet)