I have a 1/4" line on my 98 because it is what I had laying around. I have 1/8" line (like the little line commonly used on mechanical oil pressure gauges) on my 96. I put a restrictor orifice at the engine end on both trucks so If I did spring a leak it would be a slow one and it helps squelch the lift pump pulses on the 96.
There is no need to bleed the line since the air pressure in the line is the same as the fuel pressure. The compressibility of the air in the line also helps protect the gauge from pulses in the fuel pressure.
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96 3500 4WD, 47RE, gauges; 97 3500 4WD 47RE, gauges; 97 3500 2WD 5-spd; all club cab. 98.5 2500 2WD SB, 5-spd, gauges, quad cab