400 bigblock, 78 Magnum, got all the passenger side removed easy-peasy, and #1 on driver's side. Is there an easy way to remove #3, #5 and #7 plugs?

Thanks

i owned a late 70's Cordoba 400 auto, and I think I may have went from underneath and I may have removed a heat shield and bracket to clear the way. Dont know how similar magnums are though..

Same car basically, different front clip, and bumpers.

having owned several 74-76 big chryslers, they suffer from the same difficulties removing those same plugs. my only solution was several modified sockets and extensions, plus using a swivel head ratchet. not a fun job for sure. wish i could be of more help.

Used to have a 440 in my Challenger, never a fun job!
Used to love the car magazines suggesting "change them when you get to the track" Ha!
I'm sure I used a couple of different box and open end wrenches.
I think since I had to lift the car anyway I would remove as many as I could from underneath.
Manual steering gives you more room, I don't recall whether I had to loosen the headers on that side or not, definitely try it since you won't lose any coolant.

that's what I was thinking

I've got headers on all my cars. I like these. http://newperformanceproducts.com/view-release.php?id=38&show=all

I have a 400 (core engine) in a '70 Challenger with headers and PS. Plug change requires some adaptation... but not too bad after figured out. Key tools are a short "wobble socket extension", short regular extension and a box wrench that fits the hex on my spark plug socket. On several holes, I fit the socket to plug and use the box wrench to tighten or loosen.

Hardest for me is getting the tight ones started back in. Often by feel with a short socket extension in my fingers.