The 48 & 49 types were a bit different from the later types or late 49 thru 53. The early types have an air dam that covers the baffle openings at the front. The later ones are more uniform with an abbreviated air dam at the front.
http://www.vanpeltsales.com/FH_web/F...mplete1949.jpg
http://www.vanpeltsales.com/FH_web/F...te1949to53.jpg
The trucks likely used the V-band clamp to insure less unfiltered air leakage but that is only an assumption. The V-band is a more positive clamping device but it can be more difficult to install & remove the assembly. It seems like all of the V8 engines used the V-band type starting somewhere in 1952 until the end of production but I could be wrong.