GSM850 downlink band SAW filter

Hello OsmocomBB community, Now that the software issues have been solved with my obb-fcmods-r1 release, there is only one remaining feature of the historical Mot C1xx phones that is not matched by the newly-made FCDEV3B product: support for the GSM850 band. Mot C1xx phones were made in 900+1800 MHz and 850+1900 MHz versions; my current FCDEV3B is 900/1800/1900 MHz triband, but no 850 MHz band. I could easily produce an 850/1800/1900 MHz version of the FCDEV3B if I knew which SAW filter part number I should populate instead of the EGSM downlink band B7820 filter which currently sits in the low band Rx path. But I don't know this part number. I know that Openmoko produced both 900/1800/1900 MHz and 850/1800/1900 MHz versions of their GTA02 by populating different SAW filter parts onto the same PCB footprint, but I only know the part number for the EGSM downlink band filter (B7820, populated on current FCDEV3B boards), but not the one for the GSM850 downlink band. I looked at the schematics for a later quadband board from TI (I-Sample, LoCosto chipset), but the SAW filters used there have a different PCB footprint (smaller), hence their part won't work. So, would anyone happen to know a part number for a GSM850 downlink band SAW filter (be it the same one as used by Openmoko or a different one) in the same physical package as the B7820, B7821 and B7851 for EGSM, DCS and PCS downlink bands? TIA, Mychaela