68' M715 AKA "Smokey", 8.1 engine on links, coils and 40's

[Rock40]

Hi, first post on this forum but not a new build. I've been documenting this over on another forum but figured there may be more interest here.

You will probably see more of the M715 than you actually WANT TO on this thread. They are fairly odd beasts that received all kinds of modifications from the military which make them quite a bit different from a civilian "J" truck. Be forewarned, I like detail, custom fabrication and extremely robust engineering.

Currently about 3.5 years into the build and I'll be slowly moving information here over time. Not my first build but it is the first Jeep build, specs below...

1968 M715 1.25 ton truck. Bone stock, 40K, spent it's entire life in interior Alaska (Fairbanks)
2001 Tilden Motorsports 8.1 liter Vortec
Ranger OD
GM SM465
Off Road Design Magnum Box
NP205

Front Axle:
GM Kingpin Dana 60, RCV 300M shafts, ARB, Reid Knuckles, 35 spine hubs, shaved housing, etc

Rear Axle:
Corporate 14 Bolt, stock shafts (until they twist and break), ARB, disc brake conversion, Artec truss

The end plan is to run a full linked and coiled suspension on 40's. Why the nickname "Smokey" you ask? Because the 8.1 liter is going to turn good rubber into white smoke. Simple, stay tuned.

Towing it back from Fairbanks...


Pics were taken close to midnight around the solstice, fantastic time of year up there


Northern Yukon traffic jam


Making friends back him with my 69' FJ40

 

[Rock40]

Starting to tear it down. The truck did run OK but it BARELY drove and wasn't safe. Radiator was plugged and it would start to get close to overheat quick


Tornado engine coming out...



8.1 test fit, one of MANY attempting to shoehorn an engine of this size where an inline 6 once lived

 

[Rock40]

Cleaned up engine bay...


Pulling the bed, which weighs a friggin' TON


Full teardown now

 

[Rock40]

More tear down, most of the parts came apart fairly well for their age



Pile of sheet metal parts ready to be stored away for now



Drivetrain mock-up. Using empty cases (minus the ORD Magnum) to save on weight




ORD Magnum and NP205 case

 

[Rock40]

Pulling the cab....





Starting the long process of stripping/cutting off the old un-needed frame brackets. The M715 got a lot of very specific stuff the other "J" trucks didn't









Found the hand stamped frame VIN. If I'm remembering correctly, approximately 33,000 of these were produced over about a 2 year period so this is a very late production truck. Lots of them went to Vietnam and probably stayed there.

 

[Rock40]

Hauling the frame in for sandblasting. With the amount of fabrication and welding in the near future, blasting is the only way to go



Clean frame....





Cab set back in place

 

[JKbrick]

Looks like a ton of work! Welcome from Indiana


Sent from my iPhone using WAYALIFE mobile app

 

[Rock40]

Fitting the 8.1 again, making sure there is room for the radiator and fan



The 8.1 is a REAL tight squeeze for this truck





Looking down at the floorpan and roughly where the drivetrain will sit. Eventually, a total of 5 shifters will have to nest here

 

[Ddays]

:munching: Keep 'em coming! Awesome build.

 

[Rock40]

Looks like a ton of work! Welcome from Indiana


Sent from my iPhone using WAYALIFE mobile app

Thank you sir, even now it's only about 30%-40% complete. Happy to be here!

 

[Rock40]

:munching: Keep 'em coming! Awesome build.

Oh yes, lots to follow..... :yup:

 

[Rock40]

One of the main goals on this build to to keep the truck LOW and stable. Go with an absolutely minimum lift to fit the 40's AND have a flat belly profile. Those goals helped dictate how the drivetrain was going to go in


Flat belly with drivetrain temporarily supported



The ORD is fully clockable in relation to the NP205, that really helps with tucking things up into place

 

[Rock40]

Here are a few issues with clearance. With the engine as low as I wanted it, the differential housing on the factory front M715 housing was WAY too close to the oil pan. Fortunately with a GM Dana 60, the casting is further outboard which alleviates this issue





And.....the factory 8.1 EGR hangs off the rear passenger side of the motor. Since it won't be running EGR and doesn't need it, I elected to simply cut/trim the passenger side stock exhaust manifold to shorten it. The engine REALLY had to come back this far to make adequate room for the radiator and fan. The driver exhaust manifold fit fine since it lacks any EGR nonsense.



Cut and trimmed manifold, gently tacked back together. The cast iron was ridiculously hard.

 

[Rock40]

You guessed it, pretty much unavoidable to not end up cutting into the firewall to clear the 8.1 engine.





Pushing the engine back...


And setting up the motor mounts

 

[Rock40]

It could be worse and I tried to keep it to a minimum. Cuts are rough but will be cleaned up and fully boxed in

 

[Rock40]

Lots more teardown in the cab. The military had the battery box behind the driver seat. Overall, the welds on this truck are deplorable, including the factory ones. Most of the bugger welds on the battery box had burned/melted right through the cab. Plus there was half a century of junk under where the box had been





It was also time to part with the factory M715 axles so out they came and off they went!



My buddy Mark and I loading the axles

 

[Rock40]

Took the cab in for blasting once it was COMPLETLY stripped clean. Overall, not too bad. Some expected rust but it could be way worse

 

[Rock40]

Tires arrived. Maxxis 40x17x13.5 Although I'm nowhere ready for them, I wanted to get them in place and at least get an idea for size. The GM Dana 60 is also sitting under it

 

[Rock40]

Cad drawings for the front suspension which was created by my buddy Ethan. Radius arm w/panhard, essentially a 5 link. The below pic shows the arc angles or "how to avoid suspension binding" basically



This is the upper frame bracket and axle bracket

 

[Rock40]

This is how much of the poor body looks. With only 40K miles on the clock, I'm guessing much of it was just pounding off-road. Tons of cracks that need to be slowly filled back in and welded together





Gently filling it back in with the TIG on low heat