frame /floor years? changes?

[supersize75k5]

I used to know this, but what year will the frames and floors change or work?

I just picked up a blazer chassis and drivetrain and its a 78 , I thought I remember the floors changing in 77,

the frame however I can not recall? I am trying to put a boy on it and wondering what my limitations are with out making new mounts.

 

[NEK5]

On a somewhat similar note (sorry for the highjack shawn) what k5s frames were direct bolt ons for p/u cabs?

 

[pauly383]

73-77 had the raised flat floor from behind the front seats all the way back . 78-91 had the footwell from the front seats to just a 2 or 3 inches in front of the wheelwells , then it raised up and went flat to the back .

The frames of course are different as the 73-77 had the body mount raised up on a crossmember in that area . And the 78-91 does not have a body mount area there , its pushed out to the edge of the frame just like the front cab mounts .

Now there are some differences in bodies too , the 73-75 had the rocker boxes , and the 76-77 did not even though they shared the rear floor .