I don't know what size they are, but it's rather simple to figure out, just take the one off the output from the fuel pump, which should be a short hard line, and take it to NAPA.
For reference, the Factory Parts List to the left has the parts plates, which can also be found as a PDF in the Factor Parts Manual, 1948-54:
Parts Plate, 1948-1954 The fuel system is illustrated as plate 103A, and the primary fuel line itself is Group # 9.400. Group # is the weird Packard way of assigning a part grouy for a part, then you look up the actual part # for your model and year in the Parts list.
So if you look up group 9.400 in the Factory Parts list, you get
Factor Parts List, Group# 9.400 you get #446359 for chassis #2626/5426
This Post was from: https://packardinfo.com/xoops/html/modules/newbb/viewtopic.php?post_id=253001