I'm aware that you are asking for a 3/8" inverted flare style filter. Just food for thought here, I used a Wix 33481 on the my "59 3100 (Ernest). While this filter is a 16x1.5 mm it is fairly common to GM vehicles and readily available. The filter has a flow rate of 1-2GPM at 4.0 Micron filtration. The only obstacle would be having to use metric flare nuts in place of standard 3/8in.

https://www.oreillyauto.com/detail/c/wix/wix-fuel-filter/wix0/33481


~ Craig
1958 Viking 4400
"The Book of Thor"
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1960 Chevrolet C10
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'59 Apache 31, 327 V8 (0.030 over), Muncie M20 4 Speed, GM 10 Bolt Rear... long term project (30 years and counting)

If you don't like driving yourTruck, you won't drive yourTruck..| Living life in the SLOW lane