Square body on new chassis?

[loco]

Nice work!!!

 

[offroadunleashed]

I'll check for pics. This was 4-5 phones ago...

I want to do a similar swap but a 3+3. What did you do for a steering shaft? Did you keep the squarebody hydroboost?

 

[77Dmax]

The hydroboost is from the 05. I drilled new holes to mount it. The 77 had a normal booster. That was no big deal at all.


The steering shaft was a little more involved. I bought a universal joint from the local speed shop and had to weld the 77 upper shaft to the joint. The 77 double D shaft fit inside the 05 lower shaft- also a double D shape. Got it square and welded that. The collapsing part of the 05 shaft is still there, so maybe it is still kinda safe?

 

[offroadunleashed]

The hydroboost is from the 05. I drilled new holes to mount it. The 77 had a normal booster. That was no big deal at all.


The steering shaft was a little more involved. I bought a universal joint from the local speed shop and had to weld the 77 upper shaft to the joint. The 77 double D shaft fit inside the 05 lower shaft- also a double D shape. Got it square and welded that. The collapsing part of the 05 shaft is still there, so maybe it is still kinda safe?

What about the intercooler piping?

 

[77Dmax]

What about the intercooler piping?

I didn't change them at all. The 05 core support is mostly in place. The rad, intercooler, shroud etc all are mounted as they left the factory, even the stock body mounts. I merged the two supports together. The first post or two describes the process. It was a pain in the ass, i spent hours trimming the two supports to fit together. If this was an LS truck i would have tossed the 05 support all together, but the duramax support is pretty busy with all the coolers and ecm mount. Plus I kinda remember the 05 radiator was way too big for the stock 77 support. It would have required a custom radiator that I didn't want to spend the money on..

 

[dapetik]

How about meshing the wiring inside the cab? Do you still have cruise? Gauges? a/c controls?

 

[77Dmax]

The cab has it's stock harness in place, everything works as it did in 77. The ac controls needed a vacuum pump to run actuators. Thats plumbed into the stock canister.

The cruise I have not been able to get working. I have it wired up and kinda gave up on it 4-5 years ago. It since occured to me that i never gave the ecm brake pedal input, so I'm questioning if thats my issue. I may look into that again this spring. Right now I'm busy plowing the driveway with it.

 

[MarshMobbin907]

Another dude here with a 3+3 looking to do this swap in the future
Would you be ok with giving more details on how you intertwined the 05 BCM to work with the 77 cluster/dash controls, and maybe more pictures of the fabrication that was done? Really love seeing the creativity out there being done with square bodies

The cab has it's stock harness in place, everything works as it did in 77. The ac controls needed a vacuum pump to run actuators. Thats plumbed into the stock canister.

The cruise I have not been able to get working. I have it wired up and kinda gave up on it 4-5 years ago. It since occured to me that i never gave the ecm brake pedal input, so I'm questioning if thats my issue. I may look into that again this spring. Right now I'm busy plowing the driveway with it.

 

[77Dmax]

Another dude here with a 3+3 looking to do this swap in the future
Would you be ok with giving more details on how you intertwined the 05 BCM to work with the 77 cluster/dash controls, and maybe more pictures of the fabrication that was done? Really love seeing the creativity out there being done with square bodies

The 05 BCM is in the junkyard with the old cab. The 77 cluster/dash are old school and need only wired as they were stock. The OP gauge is mechanical. The D-max has a pipe plug near the oil filter i plumbed the gauge too. The temp was a little more tricky, had to tig a bung on the T-stat housing and threaded in a stock 77 sender. The fuel gauge needed a 0-90 ohm sender instead of the later 240 ohm sender. I swapped that and jumped the wire to the 77 dash. The speedo needed an electric driver. That wasn't cheap. Dakota digital makes that. I have since found out a speedo from a later square K5/burban was electric and could have swapped that in. The pulse signals are the same.
The HVAC controls needed a vacuum source. That was easy.

The rest was simple wiring. The cab is wired basically stock. The fusible links pull power from the junction block under the hood. All the 77 wires- lights, tails cab junk are all powered as stock. The crank (purple wire) fires the relay for the starter in the junction block, and the +wire for the coil fires the ignition circuit for the junction block, which energizes all the 05 crap- ecm, tcm etc. Rigging the two harnesses together was really only a handful of wires doing essentially the same jobs as they were intended..