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Advice needed on underbody Corrosion

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First of all, I’m new to this forum, so would like to say hello, and I look forward to reading and sharing advice and knowledge with you all.

I’m looking at purchasing a 1971 Convertible 302 in original state.  

It has been a real challenge to obtain actual photos of the underbody because the owner isn’t very camera smart.  However, there is one photo that shows wired black circles, one in the right corner and a second one further down.

Would anyone happen to know what these circles could be? Is is corrosion or some sort of drain plug that’s gone a bit rusty around the edges?

any assistance would be greatly appreciated, as i meed to make a decision quickly.


Marwan from France 3AF01707-8D4A-43EC-9599-7585A21B5DE3.thumb.jpeg.e3eb4b309c1b9fff310f7a7adfd503c6.jpeg




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Hello-  Welcome to the forum.  From the looks of that picture, you had better get many more pictures.  Why do you need to make a decision quickly?  You could be in for a lot of sheet metal repairs / replacements.  If you expecting to do that anyway, then it might not be an issue.  Still, you'd want to get a car in the best shape possible for your budget.

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Hi and thanks for your reply.

I actually put a down payment on the car as it was advertised on eBay. I was about to send the balance funds before putting on hold due to this photo. I don’t mind some surface corrosion but anything more will be an issue as I still need to get the car shipped over to Europe. Based on the previous response, those Holes seem to be accès panels as the are very regular. However I couldn’t locate any underbody photos of other cars to compare.. I didn’t pay a lot for the car and the owner seems genuine so I have to reason to doubt his words. I just wanted some expert advice on what the holes could be. 

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That black area is nowhere near any sort of access plug or drain hole. That looks to be just forward of the driver's seat. The critcal areas of a convertible are the inner rocker rails, and something doesn't look right here on the driver's side. It looks like the car was jacked up by the floorpan accidentally. 




Tell him you want pictures of the floor to inner rocker area, front to back on both sides, from the inside with the carpet pulled up. If he can't manage that, I'd pass. My guess is it's rusty there and he knows it. Inner rockers are a major expense. 








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Thanks for your comments, much appreciated.  You included a link to the car i purchased off ebay..

i managed to obtain a few more pictured Attached. 

would the repair require a complete floor or just a partial replacement of the damaged section?





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It looks like it needs inner and outer rockers because of the pinch weld condition, if you want to replace the floors they sell pre molded sheet metal. If you just want one very badly and can do all the work yourself its probably an ok purchase

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Ok well I’m taking the plunge and having it shipped over To Europe. I didn’t pay much for the car so it’s not a problem if it needs some floor pan replacement sections put in. Many thanks for your advice. 

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  • 1 month later...

You should never send money without an in person inspection. If you cannot go you need to pay someone that knows them. There are scams every day on Ebay and Craigslist to the tune of $25,000,000 in 2018. FBI recovered ZERO.

I have 5 convertibles. 72 & 73. 302 is usually thought of as not desirable and will not bring much. I have no idea what you paid but I purchased a California 73 mustang vert with zero rust original paint and interior, 351 C, auto, AC, PS, PDB, console, gauges, tilt column, convenience group, deluxe bumper, AM/FM, Decor Groupe, dual racing mirrors, sport wheel covers and an extra set of aluminum wheels. I paid $7,200 for it, 48,000 miles. You have to watch everyone thinks they are rare and expensive and not so. 
If you do not have answers is best to walk they are not rare and easy to find that is why I own them.


When a man is in the woods and talks and no women are there is he still wrong??:P


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  • 4 weeks later...


So my 71 Convertible arrived a few weeks ago and I’ve began the teardown process for a full restoration.

The underbody rust situation isn’t as bad as i thought, but does require s few patches made for some of the flooring.

There is some rot below both upper control arms so In a a rectangular box section and i will need to cut out a section snd weld in a replacement patch there too. The frame rails, torque boxes and sills are solid with no corrosion or damage.

The radiator core support has some lower corrosion And appears to have been badly replaced sometime in the cars life, , so I was thinking of replacing it. Could someone advise if the 1971-73 core supports are all the same? I seem to find some sellers quoting that their parts are only for the FB and coupé, not the convertible. Others don’t mention anything specific. Can anyone recommend a good quality replacement Brand?

Many thanks,





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  • 2 weeks later...

Don @ Ohio Mustang Supply (who is a site supporter) has been a good resource for questions about what vendors supply which reproduction pieces and which ones are the best quality. He should be able to answer your questions.

I am pretty sure that all 71-73's use the same core support but have been wrong before.


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