Square firewall holes?

[th3fourn]

Two square firewall holes… I am cleaning and not sure what those two square holes are in the firewall.. can I weld them shut with some sheet metal. Any info helps. Thanks!

 

[gick70]

They are for your stock wiring harness !!

 

[Oldtimer]

If you stay with stock harness, the harness plugs that go in those holes will interfere with the head on the 351W you are installing. Move them up, or around the corner into the side wall of the inline 6 bumpout in the fire wall.

 

[Broncobowsher]

Early tubs had the fuse block mounted there and the under hood wiring passed through at that point.
Late tubs moved the fuse block to the glove box and ran the wiring differently.
I suspect the change is when they went to electric wipers, but never dug that deep into it. My old '69 (factory vacuum wiper) had the square holes. The '71 didn't, from what I remember.

 

[th3fourn]

Awesome thank you everyone! Have the new harness so going to cover up

 

[jamesroney]

Early tubs had the fuse block mounted there and the under hood wiring passed through at that point.
Late tubs moved the fuse block to the glove box and ran the wiring differently.
I suspect the change is when they went to electric wipers, but never dug that deep into it. My old '69 (factory vacuum wiper) had the square holes. The '71 didn't, from what I remember.

The fuse box moved for the 1971 year model.

This May built 1969 had electric wipers, and the firewall mounted fuse block.
My 1970 also had a firewall fuse block.

The plug is in the way for the 5.0 SEFI upper plenum, as well as the 351W. This one is relocated as advised by @Oldtimer

 

[Broncobowsher]

So much for my theory of it following the change to electric wipers.

 

[DirtDonk]

Yeah, we’ve been trying to track down the actual changeover for a long time.
So far the only deciding factor was between the 70 and 71 model years. No exact serial number, or if it was a running change between years or not.
But the old wiring diagrams kept the old orientation for the 71 model year as well.
I have a late 71 and a friend had an early 71 and I never bothered to check his wiring before he sold it.

 

[toddz69]

Sounds like a good research project to figure out when those changed - I always assumed the start of the '71 model year but who knows.

Todd Z.