bolt in transmission humps

[rustymitchell]

Hello,
Does anyone know when the bolt-in transmission humps were replaced with the one piece floor pans on a standard trans 4x4 truck? 

I've noticed that the 73-80 4x4 cabs have a two piece hump with the rear part being spot welded to the floor from below the front piece being bolted in from the top.  The later model 4x4s that I've seen have a stamped one piece high hump transmission tunnel.  I've also noticed that the 81-87 2wd cabs have a stamped rear hump blended to a lower forward section. 

Has anyone here ever had a 81-87 4x4 with a factory bolt-in tranny hump?

The reason I am asking is that I have a 85 2wd cab going on a 79 4x4 with a sm465, np205 drivetrain.  I don't like body lifts so that's not really an option for me.  I can modify the 79 transmission hump to fit the 85's floor (the floor contours are slightly different and the rear part of the hump is quite different than the 79's) but I want to find out if there is a 81-87 bolt-in cover I can use instead.

Thanks for any info!

[thirsty]

Here is a thread about humps.

http://forum.73-87chevytrucks.com/smforum/index.php?topic=11838.0

[rustymitchell]

Thanks Thirsty,
It looks like there is a post-80 bolt in style judging by the yellow '83 that's pictured there.  Probably hard to find one though!  It also seems that there were some small changes in the floors during years 81 to 87 as well.  It seems they went from a bolt-in style to a one piece stamped floor during the mid 80's and not at the 80/81 re-style.  It seems they also got rid of the stamped lines (where the floor would be cut for the high hump) on the low hump cabs too.  The 81 2wd in the pictures has the line but my 85 does not.  I'll keep my eye out for an 81 to 83 4x4 and have a look. 

[Captkaos]

I think 1983 is when it changed, but don't hold me to that...

[rustymitchell]

I think you are exactly correct!  I've been scouring through pictures on your site and it seems the floor pans changed between the '83 and '84 years.  84 and newer cabs don't seem to have the stamped line where the low hump is cut out.

[Captkaos]

reason I say 1983 is because that is when they officially went to galvanized floors.  Don't be surprised to find a 84 with either though...

[Blazin]

I have cut many of the one piece floors out and trim them down until they fit good. Then use butyl tape, and large self tapping screws to bolt it down.

[Cabcorner]

I've put two humps in two wheel drive cabs.the first was an 85 hump in a 87 cab .You would be surprised how well the molded hump fit the two wheel drive cab,even the creases lined up.The second hump was out of a 78 4x4 that I put in a 86 cab .This one I had to make a extension piece that went from the back of the hump to the floor under the seat.