Topic: Early 67 C4 Neutral Safety Switch wiring change dates

[sparky65]

So I broke this discussion out of another post where I was posting pictures of my firewall.   This is the picture that started the questions.


Midlife pointed out something looked odd with my NSS wiring:

My eye caught the wiring connectors coming out of the firewall.  Usually, the molded plugs are color-coded so that they match across the joint.  Your backup/NSS plug from the firewall needs a molded four-prong connector; you appear to be using an earlier (67?) backup/NSS harness that uses two separate 2-prong connectors.  Something isn't right here...

Jeff then followed up with an example from the same month as my car:

Noticed you missed one of the screw covers (should be two) (Purple arrow)





And a picture of the reverse/back up light plug from an Oct car - Notice how the plugs differ from your (Green arrow) plugs above

It appears at some point the NSS was changed from two connectors to one.   I started to think mine was replaced with an incorrect one which is probably still the case although it doesn't appear to be a reproduction.  The picture Jeff shows is from an Oct car which I believe was probably built before mine so more then likely I have the wrong one.  However I was looking at the Scott Drake reproduction: C4AZ-7A247-C     They label this two plug style as, "1965-1967 Mustangs with a C4 Transmission built before 12/15/1966".  Which would indicate I have the right one but I have no idea where they got there info from.  So now I am looking for more then two data points on this.  Which type does your car have? 

Related to this would be the question if any early 67 cars would have received the two plug style?  And if so would the dash side of the plug also be the two plug style or would they have put it together the way mine is now.

[midlife]

I have over 2 dozen 67's in refurbishable condition.  The first 12 I could access all had the four prong plugs in black for BU/NSS coming out of the firewall.  I could swear I've refurbished for someone the two separate plugs...

[ruppstang]

I have never seen a 67 with two plugs. I have a SJ convertible that was built 11-4-66 and it has one plug.
Marty

[krelboyne]

My Mercury MPC indicates before 12/15/66 used C6AZ-7A247-A (SW-549) "includes wiring w/2 single head plugs".

I have one example like that on a 1967 Cougar, but it is not original to the car, car has a much later VIN. Probably replaced.

[J_Speegle]

Only focusing on the main wire harness and not the neutral safety switch lead specifically I found the following

NJ examples through the year

7T01T131041



7T01C149061



7T01C168448



7T01T181321



A Dearborn example - just for the heck of it

7F01C110738




San Jose through the year just for comparison

7R02S114562



7R01A153347



7R01C198642



7R02C230957

Have lots more but this should give a wide set of examples through the year for comparison

[69SCJQ4.30]

Only focusing on the main wire harness and not the neutral safety switch lead specifically I found the following

Don't really want to get into a big argument here but yes focus on the main wiring harness plug, nobody said those weren't all a four prong connectors!

The discussion is over the NSS and ford books call out they used the two plug switch before 12/15/66 which still plug right in the four prong plug if you even look in the MPC you will see a separate part number for a early 67 C6 NSS which was the part number posted earlier and by golly it has two separate plugs!

Paperback Writer a member of this forum I rebuilt his transmission a month ago he has a real early 390 car two plug NSS and we have a 67 coupe here at our shop Nov 26 build two plug NSS.

[J_Speegle]

Don't really want to get into a big argument here but yes focus on the main wiring harness plug, nobody said those weren't all a four prong connectors!

No reason for any "argument"  - not what we're here for   Can simply now focus on the plugs though unfortunately allot of them have been changed out

The discussion is over the NSS and ford books call out they used the two plug switch before 12/15/66 which still plug right in the four prong plug if you even look in the MPC you will see a separate part number for a early 67 C6 NSS which was the part number posted earlier and by golly it has two separate plugs!

Paperback Writer a member of this forum I rebuilt his transmission a month ago he has a real early 390 car two plug NSS and we have a 67 coupe here at our shop Nov 26 build two plug NSS.

We'll we know the 390 is a San Jose car so where was the coupe you mentioned built?

[69SCJQ4.30]

It is a San Jose car as well.

[sparky65]

So I always try to understand what the reasoning is behind some of these things and as usual this is one of those things that doesn't make sense yet.

 

Don't really want to get into a big argument here but yes focus on the main wiring harness plug, nobody said those weren't all a four prong connectors!

The discussion is over the NSS and ford books call out they used the two plug switch before 12/15/66 which still plug right in the four prong plug if you even look in the MPC you will see a separate part number for a early 67 C6 NSS which was the part number posted earlier and by golly it has two separate plugs!

Why would all the books call out to use the two plug switch before 12/15/66 if the harnesses were all 4-prong?  Does anyone know if there are some other differences with the NSS related to some change in the trans that happened on 12/15/66?  If it was just a leftover 66 part that fit why did it continue so long int 67?  Clearly they had the intention to go to a 4-prong plug otherwise they wouldn't have changed the main harness.  Maybe some one in the engineering department forgot to make the change to the NSS and as long as it pluged in and the line continued to move they made the change when they got around to it.  I still wonder how the date was established.  Is that when the engineering change was supposed to go into effect?

[69SCJQ4.30]

So I always try to understand what the reasoning is behind some of these things and as usual this is one of those things that doesn't make sense yet.

 
Why would all the books call out to use the two plug switch before 12/15/66 if the harnesses were all 4-prong?  Does anyone know if there are some other differences with the NSS related to some change in the trans that happened on 12/15/66?  If it was just a leftover 66 part that fit why did it continue so long int 67?  Clearly they had the intention to go to a 4-prong plug otherwise they wouldn't have changed the main harness.  Maybe some one in the engineering department forgot to make the change to the NSS and as long as it pluged in and the line continued to move they made the change when they got around to it.  I still wonder how the date was established.  Is that when the engineering change was supposed to go into effect?

I don't really understand the two different switches either I mean using it if its left over is one thing or if the four prong plug switches weren't into production when they started making 67s is another option but why mark it in the book if it wasn't there original plan? I can only answer why the switches are different for 70 with a for sure answer.