1978 cordoba gas tank interchange

[msthec1]

i know this is a old post but i just bought a 78 magnum and i want to put dual exhaust on it is the floor different or just the tank. i had a 79 300 years ago that had duals on it but i dont remember anything about the gas tank my magnum has a big tank and its off to one side it almost touchs the pass. side frame rail. do i just get the smaller tank with the hump on top or is the trunk floor different i cant see chrysler putting in a different trunk floor just for cars with dual exhaust. i dont know

 

[dodge1972]

There are several posting in the b-body history regarding gas tanks. Real great comments. If you interested in converting to due exhaust you need a smaller gas tank. The bubble top tank was stated with the 73 or 74 b-body line. Not sure but I believe in 75 the tank was enlarged to increase the distance per fill up as a marketing ploy. I have a 74 with a new tank. Price range is $300+ Costly compared to older tanks. Check Rock Auto for best prices or on ebay. Ebay prices vary on vendor. Tank mounting hardware is the same for both tank. Replacement sending units will required some adjustments. Install and check movement from the filler hole Good Luck Robert in Denver

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Also check the tank dimensions if you want to smaller tank. The left side is shorter on the smaller 20 gallon tank.

 

[Crizila]

79 300 tank ( for dual exhaust ) will bolt in to your magnum. I believe the floors are different, but not in the gas tank area. The floors were humped up some on the 300 for dual convertors ( which sat under the seat area) on the dual exhaust 300's. - which is why the 300's did not offer power seats as an option( no room for the PS gear)Also, the 300's sold out of Ca. had 3 convertors ( my wife's did ) along with black valve covers and no "premium 360" stickers on them - although the engine was an E58 motor. BTW, I have a 300 tank, straps, and modified 3/8" ( originally 5/16) fuel bung and all the original heat baffles ( and there are a lot ) for the original exhaust.

 

[msthec1]

i had a 79 300 in 1989 it had the dual converters and now that i remember it did have a smaller tank in it. my magnum has a huge tank in it and its off to one side there's a 79 300 in a junk yard about an hours ride from Milwaukee if the weather stays mild here i might go check it out and see if the tank is still in it and what he would want for it.

 

[barbiebandit]

CR21A is the 1974 fuel tank... I changed my trunk floor to a 71 - 73 floor eliminating the hump completely and went and got the CR10B tank which is almost identical in profile and capacity even uses the same straps and is WAY cheaper than the one with the hump back lol

Hi following up on your 10 year old post. I have a 74 and am trying to avoid buying the CR21A tank and swapping in the flat-top CR10B tank. I am not changing the trunk floor though. Any tips or issues you encountered during installation or afterwards?

Here is my thread on this:
https://www.forbbodiesonly.com/mopa...nk-onto-a-74-satellite.172423/#post-911251383

 

[dodge1972]

The hump design is for the vent to the recycling canister plus its an expansion tank. early tanks from 71 & 72 will fit, but these tanks used a seperate expansion tank. I installed a flat tank in a 74 charger with no expansion option, but I do smell gas from time to time.

 

[barbiebandit]

The hump design is for the vent to the recycling canister plus its an expansion tank. early tanks from 71 & 72 will fit, but these tanks used a seperate expansion tank. I installed a flat tank in a 74 charger with no expansion option, but I do smell gas from time to time.

Thanks for this!