'78 K20 sheetmetal question: bed and tanks

[Minnesota]

Searched around, but no true satisfaction. Been casually searching for a replacement bed for the truck prior to other body work, then paint hopefully some time this year. Bed's the only thing that we are calling "too far gone".

I'm aware of hood/front end changes in the 3rd Gen, but am now trying to do the mind meld on beds. Truck has dual tanks, round "exposed hole" gas fillers, with passenger side currently functional, and clearly the factory one as it is stamped as to be nicely recessed when you twist in the cap:

1. Were there any body-line changes in this time period? My current impression is no.

2. Gas fillers. According to LMC, there is a '76-78 "round hole" and a '73-78 "blank". "Blank" meaning nothing further stated where the same column lists "round hole". Generic picture is square flap door drivers. My current thinking is that a '78 was factory stamped for passenger side exposed round filler, then somewhere along the line, a second larger square-corner tank was added driver side (not recessed). Factory or no? Likely not? Have a toggle switch in the metal below my headlight switch that tends to confirm aftermarket suspicions. Sorry for the novel, but if I find a decent 3rd Gen bed, flap door or no, are said locations drastically different to plumb into existing tanks? Tend to think no, but I was only 7 years old in 1978 and never had a chance to notice such details.

Thanks for any thoughts!

 

[dremu]

I can partially help.

I had a '74 pickup with a later (80's?) bed with the square flap doors over the fillers on both sides. It had the later style plumbing to match the bed, but it connected to the original tanks just fine.

If you replace the bed you may have to juggle the plumbing to match it, but you should be able to use your existing tanks.

-- A

 

[Minnesota]

Cool. That's what things look like. Thanks for the feedback.