Which gas cap fits under flip top.

[Fern]

Looking for a locking gas cap that will fit under the flip top lid. Its for a 70 Challenger. I have done a lot of research but the numbers listed on forums never match the car as fitting. Has anyone used any brand and part number of an aftermarket cap that works?
Dont care about original, just something that fits.
Thanks

[PlumCrazyRTSE]

I used one of these before I found an original.

http://www.ebay.com/itm/Parts-Plus-P5771-Locking-Gas-Cap-fits-many-classic-1965-1980-U-S-Made-Vehicles-/161059787509?pt=Motors_Car_Truck_Parts_Accessories&fits=Year%3A1970%7CModel%3AChallenger&hash=item257fe952f5&vxp=mtr

 It worked fine but you do have to use the key to put it out because you won't be able to get your fingers around the outside of it.  That wasn't really a big deal because the key has to be held to the unlock position while removing it anyhow.

[Adam]

I used a Motorad MGC-771, locking gas cap, for my 71 Challenger.  It forms a nice seal on the filler neck and fits under the Flip Top perfectly.

[1 Wild R/T]

I used a Motorad MGC-771, locking gas cap, for my 71 Challenger.  It forms a nice seal on the filler neck and fits under the Flip Top perfectly.

But the 71 filler neck takes a different cap than a 70 and a 70 has two options 49 state & California, both 70 caps are different from a 71-74 cap..... Which leads to a common issue with these cars, if the car has been put back together at some point in it's life who knows which year filler neck is in the car... The only one that can be visually ID'ed is the 70  Challenger 49 state filler as it has a vent nipple...

[Adam]

Yes, the 70 may take a different cap, thats why I specifically indicated it worked on my 71.  Further I am 100% certain my car has it's original filler tube. 

Some filler tubes have a very shallow lip on the inside which forms the locking cam area; this lip is less than 1/4 inch.  Other filler tubes have a deeper/wider lip inside, maybe 7/16ths or so.. there are pics available on this forum
(http://board.moparts.org/ubbthreads/showflat.php?Board=A12&Number=6362586&Searchpage=1&Main=6362586&Words=+ebodiesonly&topic=&Search=true)

So if your tube has the deeper lips, which forms the locking cam inside the filler neck, the Motorad-MGC-771 will work.

[Chryco Psycho]

Rock Auto has a couple left

[1 Wild R/T]

Just gotta show what was originally under all flip top gas caps...

[1 Wild R/T]

And..

[Chryco Psycho]

so those would be different year to year also if the filler neck has a different lip

[1 Wild R/T]

There are at least three versions of the Challenger only locking gas cap....