Anyone know the frame length differences between 620's?

[Justin]

Hey datto brudders,

   So 620's had short bed, extended-cab, long-bed, & extended-cab long-bed (and probably some other crazy shit that doesn't apply to me that I don't care about,).

 

How much longer is an extended-cab frame than a normal shortbed (I'm assuming longbeds & extended cabs use the same frame, if that's wrong please let me know)?

 

Thnx!

 

[Preacher]

SB 169.2”

LB 185”

KC 178.7”

 

These are the numbers for the overall length of each truck. 
 

There wasn’t a factory made KC long bed. 

[datzenmike]

This is the body length. Frames will be less.

 

 

The ends of the frames might vary but the wheelbase does not. There are two different wheelbases but three trucks based on this.

 

 

Regular cab short wheelbase 100.2" (between front and rear wheels)

 

Regular cab long wheelbase 109.6" uses an extended box about 9.4" longer than the short wheelbase truck.

King Cab long wheelbase..... 109.6" uses an extended cab which is about 9.4" longer than the regular cab and a short wheelbase box.

 

There are 6 cab mounting points and 8 mounting points on the box. I can give you the distance from the very front to the very back mounting points. The King Cab and 'Long Box' extend past the rear most mounting points different lengths. The Long Box frame itself may extend farther so that the rear bumpers are properly positioned under the tail lights on the box.   

[Preacher]

Yes, the long bed frame does extend farther than the KC. 

[datzenmike]

I guessed as much having put a '78 king cab on a later '82 long bed frame. Wasn't sure as this was also 620 to 720 and there were bound to be differences anyway.

[Justin]

Good stuff, 'preciate it!

[EDM620]

There are only 2 actual frame lengths with the regular cab short box being the shorter frame. The KC/short box and the regular cab/long box frames are the same length, only the 2 rear-most mounts for the cab are in a different position. All other body attachment points are the same. The 720 frame is largely unchanged but the tail of the frame is slightly longer to accommodate a rear bumper from the factory, plus an extra pair of mounting holes at the very front. Again, the body attachment points are unchanged - style is different but the geometry remains unchanged. I believe the D21/Hardbody chassis also retained the same body mounting points, but I don't know if anyone has confirmed that. If so, that would be a great way to update the running gear by 2 generations.