Builds Build: Transforming LJ78 into HZ 77 LHD 5 speed. (1 Viewer)

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BiffS

Too many projects... ooh, look. Something shiny.
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I'll keep the preamble brief.

Fresh off our last swap with a PZ into a LJ78, we are now embarking on converting a great low mile LJ78 into a HD front nose 77 style with turbo HZ and 5 speed. Might as well LHD swap it at the same time.

Details:

low KM 1HZ donor that has been serviced (T-Belt, water pump, rings, valves, HG, etc)
Grunter turbo
intercooler
5 speed: maybe H151 or H55, have to figure it out still
lockers
mild, if any lift
77 style HD front clip
maybe some extra goodies too.

Donor truck was purchased with 130,000 KM on it. Drives great.

our plan: go thru the whole thing and convert to a coil sprung proper diesel powered example. Might as well make it LHD at the same time. Truck will be for sale once completed.

progress photos are a bit late so far, but here they go. I'll answer whatever tech questions I can as we go.
Engine, trans and other bits will be for sale as we go too.

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This is my 77 from many years ago, and roughly what it will look like once done.

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Frame horns that will need modification. track bar and steering box will have to be swapped right to left.
second pic is my 77 on hoist for example of where the frame horns will need to go. 73 series fender test fitted for example.
Axles being fully rebuilt. Factory front e locker installed with 4.88s

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Size difference example of the 2LT versus PZ/ HZ style engines.
second pic is my 77 with a 1HDT swapped in. This project will be similar, but different all at once... the light duty frame will need some mods to accept the extra length of the HZ.

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how did you convert to the square nose?
The front clip are interchangeable. The 77 and 78 bodies are the same firewall back. So in this case, it really is just a 77 since everything on it is 77 now.

We did a different build where we put the HD nose on a 78 frame and had to make new front frame support for the body, and engine mounts but otherwise it all fits the same.
 
The front clip are interchangeable. The 77 and 78 bodies are the same firewall back. So in this case, it really is just a 77 since everything on it is 77 now.

We did a different build where we put the HD nose on a 78 frame and had to make new front frame support for the body, and engine mounts but otherwise it all fits the same.
Early 78 are still 78 and not a 77 just because you put a wide nose on. Yes bodies are the same but that doesn’t make a 78 a 77😉
 
Early 78 are still 78 and not a 77 just because you put a wide nose on. Yes bodies are the same but that doesn’t make a 78 a 77😉

I'd argue what he made is better than both. 1HDT > 1HZ/2LTE. Looks like he put the 9.5" FF rear axle in. Front is still coiled for soft ride. 78 front axle shares everything with 77 except the housing/springs/shocks/ratio. Moving parts are all the same: Diff, axle shafts, birfs, knuckles, brakes, rotors, bearings, spindles, hubs, etc.
 
Early 78 are still 78 and not a 77 just because you put a wide nose on. Yes bodies are the same but that doesn’t make a 78 a 77😉

Hello,

78 Series Light Duty front is shorter than that of their Heavy Duty cousins. If I remember correctly, it is some 10 inches.

Yes, you can squeeze a 1HD or a 1HZ engine on a Light Duty 78 Series, but it is a very tight fit.

A better approach involves getting the extra frame length piece from a Heavy Duty (Edit) donor truck and some fabrication.







Juan
 
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Yes, we have a great deal of experience with both series trucks: I have a 77 that's on its third body due to some attempted inverted driving. (Do not recommend).

I was only referring to the bodies being the same, firewall back. The 78s are 12V native as well versus the 77s 24V system.

Much of the running gear on the 78 is lighter duty versus the 77.

Less gusseting on front axle, 8" rear diff, and obviously linked versus leaf.

Frames are similar, structurally, besides the 6" shorter of the 78 and some fewer gussets on the frame versus the 77s.
 

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