Jon, point well taken, your experience is respected and valuable.
To beat the horse and to help others in the future who choose to use the search feature. (the next guy) DADS50 is absolutely correct. Spectra is the best and others are not.
Spectra Premium are the best tanks. ALSO, some aftermarket tanks have metric threads! BEWARE. This tank has 1/8" NPT (National Pipe Thread) pipe threads which are correct. There was a little spec sheet that came with it saying it is good for use with up to E20 fuel and biodiesel 5% I believe. This tank is made in Canada. They are very, very nice and many, many guys on stovebolt.com recommend them highly. I was floored by the quality. You won't be disappointed. Mine fit perfectly! 1954 is siphon feed from the fuel tank. 1949 - 1953 were all gravity feed from the tank. All these tanks have a threaded fitting at the bottom. These trucks come with a pipe plug in the bottom for 1954 and 1955. Remove the plug if you really want a gravity feed fuel system. Chevrolet updated it in 1954 since gravity feed is dangerous because if the fuel line breaks for any reason, such as in an accident, the entire tank of fuel will drain. If you're interested in converting to 1954 style, get the later fuel sender and bend up a new fuel line.
Why maintain this crazy petcock valve, leaky, dangerous old style plumbing? It's so easy to swap over. Too many post reveal this is an unnecessary problem magnet. This is an area where originality is unseen and ridiculous.
The LMC tank note "A" advises that tank is for either plumbing system. If there are actually two holes in the bottom, I do not see the reason for this. One hole for either a fitting or a plug would seem to make more sense. At any rate, it does seem that a user of an LMC tank could either switch to top outlet or use the plug hole as the bottom outlet and plug the other funky fitting. (may require a new hole in cab). Spectra tank has one 1/8 NPT hole.
