Fixed it for you.

D3TZ-9080-A .. Cover-Fuel Tank Filler Opening / Approx 4.00" (steel) used when mid-ship inside frame rail tank not used.

Stylesides: 1973/76 F250 4WD (Regular & Crew Cabs) / 1974/76 F100/250 / 1974/76 F350 Stupor Duper Camper Specials.

No such thing: All 1977/79 F100/350 Stylesides have fuel doors / 1977 F250 4WD (Highboy) cancelled mid-model year (February) 1977, before serial number Y20,001.

D4LY-65405A26-A .. Fuel Filler Door-Use with fuel filler pipe / 1977/79 F100/350 Stylesides // Same fuel door as: 1974/76 Continental Mark IV & 1977/79 Continental Mark V.

D7TZ-99405A26-A .. Fuel Filler Door-Used when fuel filler pipe not installed / 1977/79 F100/350 Regular Cabs / 1977/79 F250/350 Crew Cabs.

 

Oh boy!!! A truck with 3 gas tanks! Anyone got one of those??? Probably only available on a '77.5'-'79 F-250 / F-350 dually short wide bed 4x4 Hi-boys.
But wait...The manual is a '73. OMG... a factory misprint... or a sneak peak at things to come?

Seriously now. This answers my original question. Thanks Mikeo0o0o0.

I appreciate all the replies.

Roger

 

Well that's the thing, as there are no fuel filler openings to cover on the midship tank when it's not used. So it doesn't make sense. There is a hole to cover on trucks that don't use the aft tank.

Seen too many of them. Owned one. My father owned another.

Pictures are worth a thousand words though... No D3TZ-9080-A cover shown on any of these randomly picked sources from the archives... No mid-ship tanks installed.









Except the 1973-1977 (Highboys before serial number Y20,001) and Crewcabs with in-cab gas tanks, and no auxillary tanks.

Pictures with the D3TZ-9080-A cover on the aft tank hole...







http://www.lov2xlr8.no/brochures/ford/77fp/bilder/2.jpg

I seem to recall that we've had this discussion before. I'm willing to bet that there is an error in the book, and it should read AFT instead of MID-Ships.

Trucks without midship tanks never had the hole stamped from the factory, so why does it need a cover.

F-250 Highboys, and Crewcabs with in-cab tanks only, use the same left bed side quarter panels as the 1973-1976 F-100 with a standard aft tank.

The only conclusion is the D3TZ-9080-A is for the aft tank hole for trucks without aft tanks.
Anyone with a F-250 highboy, or Crewcab without an aft tank, care to show close up pictures of their D3TZ-9080-A cover please.

EDIT: We did have a similar discussion before, back in 2008.

https://www.ford-trucks.com/forums/7...ml#post6228881

 

This question gets asked a lot through the years and it always ends up some people say one way others say the other way in the '78-'79 4x4. Mine is rear aux front main and thats the way it left the factory. Personally I like it as the main being the bigger tank.

 

Actually it's 1977 when they changed the fuel opening where it gets muddied up.

1973-1976 is a given. Main tank is the aft rear tank, except on crew cabs and Highboys, where the in-cab tank is the main, regardless on how the switches were wired, and the hoses placed etc...

Actually you got that backwards. Three tanks were theoretically possible 1973 to 1977 models before Feburary 1977.

The Federal Government made in-cab tanks illegal circa January 1977.

I've seen trucks with as many as four. Three factory type, and one aftermarket mid-ship tank on the passenger side.

These rolling fuel tankers were born out of nessecity due to the 1973 Oil Embargo. Didn't know when your next fillup was coming, or if you could get any gas from week to week. Similar thing happened in 1979.

 

[quote=81-F-150-Explorer;12150928]Actually it's 1977 when they changed the fuel opening where it gets muddied up.

And including trucks like my '76 F-100 reg cab shortbed 4x4 with an in cab tank that is designated as MAIN

 

Yes, I was forgetting the other in-cab tank variants.

 

I've got the cover on the rear and I got two fuel doors. One on the passenger and driver side. But the tanks are gone. Would like to replace them

 

The ones you have are aftermarket tanks, not factory. I had a setup like this years ago and one of the first things I did after buying the truck was remove them. I didn't like the mounting location at all. Between the bedside and frame rail isn't the best location for a fuel tank.....ask a Chevy or GMC owner that's been broadsided.