Yes, you want to be sure the sender does not fall out. It could lead to major engine problems.
It seems very odd to me that the filter housing would strip before the sending unit itself. The senders I have seen are made of some kind of alloy. Wouldn't that strip long before the filter housing? Are you sure there wasn't an existing problem when the first one was leaking?
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13