71 Road Runner Beep Beep Horn Application

[Conv440]

Recently picked up a 71 RR 340 4 speed. The car was missing the beep beep horn, however it did have a standard large-washered bolt in the upper horn mount on the inner firewall. I ordered a horn for a 71 to 79 RR and received it yesterday but it does not seem correct for this application. The mounting bracket seems too short for the large washer and it is threaded which won't work with the also threaded firewall mounting point.
It looks like Plymouth moved the horn to mount under the fender sometime in 1972 based on this thread:
1972 GTX Horn Beep Beep or not?

Since my car is an early build date, 10/13/70, is it possible I need to order the 69 - 70 horn instead?

 

[Conv440]

I called Classic Industries but they couldn't offer any advice or suggestions. I guess I can drill out the threads on the horn and mount it on the inner fenderwell with a bolt that has a smaller washer. It just doesn't seem right to have to modify the horn if it's supposed to be an accurate reproduction, especially when it cost nearly $100.

 

[T2R9]

71's use the long bracket like 70's so many resellers advertise this wrong.

 

[Conv440]

Thanks, will get the 69/70 long bracket. God the years I spent in the 90's searching for that exact dual snorkle air cleaner for my 70 440 Challenger. And then the endless efforts to get a perfect crinkle finish on it, nice job!

 

[71Beeper]

I used the same horn on my 71.
Here's how I did it.
My 1971 Road runner
It's about halfway down the page.

 

[mopar jack]

my 71 rr early build 8/70.