The FHT-34 ususally uses filters that are about 10" long and 2.5" wide. Is that the dimensions of the filter inside your housing? If so, the C1 should be a great filter for this system:
C1 water filters and Pentek C-1 carbon water filter 155002 for drinking water treatment
We do have filters that are 4.5" wide like you mentioned below. I think that is the width of your housing though and not the filter inside. If that is the width of the filter inside, please let me know and I will direct you to a filter of that size.
Thank you,
WaterFilters.NET