Found out my 81' is actually an 84'

[zieg85]

I wasn't aware of any differences between 84 and 85 in the column itself.  What differs is that the windshield washer function on the 84 works off the wiper motor while the 85 on up has an electric pump in the washer bottle.  That may differ the wiring some in that function but should only be the difference.

[SinisterC10]

Ok well I wouldn't want the 85 column then as then I would have to change out the pump.

[hatzie]

Ok well I wouldn't want the 85 column then as then I would have to change out the pump.

Not correct...
You can fit a 1978-1991 column.  It depends on what you already have and how much you're willing to change.  If I hadn't found a 1979 manual tilt for my 1976 I would've happily fitted a 1984 and up column and deleted the floor button and dash switch.  You will need to match the stub end of the column or snag the, rag joint to column, intermediate shaft because some had a splined round end and some had two flats sometimes called a double D.

Electrically;
The harmonica plug pinout does not change across the whole 1978-1991 run...  that's the 78-86 CK & 87-91 RV chassis.
The 78-83 will have ONLY turns on the column.  These require the dimmer button on the floor, and wiper switch on the dash.
The 84-91 will have the multifunction turn signal stalk.  If you have wipers on the dash and dimmer on the floor it's up to you whether you re-wire to use the stalk switch for these functions or just ignore the switches on the column stalk.  It will bolt in and work without moving the wiring.

GM removed the Washer wires from the wiper motor and moved them to the washer bottle in 1985.  The only difference is the washer pump plug and how long the engine bay wires needed to be.  This is all in the Engine Bay wiring not inside the cab.

The washer switch connects the WASH wire to GROUND.  The change makes ZERO difference in the cab wiring. 

I wasn't aware of any differences between 84 and 85 in the column itself.  What differs is that the windshield washer function on the 84 works off the wiper motor while the 85 on up has an electric pump in the washer bottle.  That may differ the wiring some in that function but should only be the difference.

The 1984 GM Light Truck wiring diagrams show a dash switch for the wipers and a turnsignal stalk dimmer switch. 
The F & G body cars, like my 1982 Cutlass Supreme G body, were already using the multifunction turn stalk with Wiper, Washer, Cruise, Dimmer, added to the Turn switches and buried in the column shrouds.  It seems a little odd that GM would make the 1984 truck column an orphan by only moving the dimmer from the floor and not moving the wiper switch from the dash at the same time. 
I've owned a 1982 & 1985 but not a 1984...  I would remember an oddity like that.

[SinisterC10]

Ok well I wouldn't want the 85 column then as then I would have to change out the pump.

Not correct...
You can fit a 1978-1991 column.  It depends on what you already have and how much you're willing to change.  If I hadn't found a 1979 manual tilt for my 1976 I would've happily fitted a 1984 and up column and deleted the floor button and dash switch.  You will need to match the stub end of the column or snag the, rag joint to column, intermediate shaft because some had a splined round end and some had two flats sometimes called a double D.

Electrically;
The harmonica plug pinout does not change across the whole 1978-1991 run...  that's the 78-86 CK & 87-91 RV chassis.
The 78-83 will have ONLY turns on the column.  These require the dimmer button on the floor, and wiper switch on the dash.
The 84-91 will have the multifunction turn signal stalk.  If you have wipers on the dash and dimmer on the floor it's up to you whether you re-wire to use the stalk switch for these functions or just ignore the switches on the column stalk.  It will bolt in and work without moving the wiring.

GM removed the Washer wires from the wiper motor and moved them to the washer bottle in 1985.  The only difference is the washer pump plug and how long the engine bay wires needed to be.  This is all in the Engine Bay wiring not inside the cab.

The washer switch connects the WASH wire to GROUND.  The change makes ZERO difference in the cab wiring. 

I wasn't aware of any differences between 84 and 85 in the column itself.  What differs is that the windshield washer function on the 84 works off the wiper motor while the 85 on up has an electric pump in the washer bottle.  That may differ the wiring some in that function but should only be the difference.

The 1984 GM Light Truck wiring diagrams show a dash switch for the wipers and a turnsignal stalk dimmer switch. 
The F & G body cars, like my 1982 Cutlass Supreme G body, were already using the multifunction turn stalk with Wiper, Washer, Cruise, Dimmer, added to the Turn switches and buried in the column shrouds.  It seems a little odd that GM would make the 1984 truck column an orphan by only moving the dimmer from the floor and not moving the wiper switch from the dash at the same time. 
I've owned a 1982 & 1985 but not a 1984...  I would remember an oddity like that.

But the 84 DID have the dimmer AND wiper switch on the turn signal lever, or at least the column that came in this truck has it along with cruise control. My nieces husband Has an 84 and it's the same.

[hatzie]

But the 84 DID have the dimmer AND wiper switch on the turn signal lever, or at least the column that came in this truck has it along with cruise control. My nieces husband Has an 84 and it's the same.

That makes more sense.  The intern screwed up the wiring diagrams and management didn't notice.