[prophet455]

What was the change in the turn signal switch between the years? Can the 77 up cam be used- was it wire location or connector change- possibly it physically changed internal to the column? Additionally what changed in the neutral safety switch?

[GStage1]

1970-94 use the same turn signal switch.
Are you missing parts?

Tilt and non-tilt columns use different horn contact cams.

Let me know.

[prophet455]

I am rebuilding a column to put into teh 74 bird, Id like to replace the old factory plastic that is looking rather tired and brittle. There are several breaks for listings for replacments in the catalogs and most of them even specify that Ill need an adapter harness to use them. Id like to know why and what changed? For instance 72 breaks to a different part # than 73 and 74...

[GStage1]

The only difference is the harmonica connector....see attached pic...otherwise
the turn signal mech are exactly the same from 1970-1994.
The center alignment pin/space is slightly large starting in mid-late 1973 models.

You can easily swap harmonica connector from your old one to a new one.

[prophet455]

That's exactly the info I was looking for- thank you -
what about the neutral switch- what changed there?

[GStage1]

Starting 74 there were two additional connectors from the NSS....never found out where they went or what they activated....then in 78....GM went back to two pin set-ups....one for reverse lights and one for NSS........so you can transfer your switch is needed or use the 3 pin set-ups and don't work about the third connection.