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1968 Dodge D200 with a 318 from who knows where?

chukardogs

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Dec 2, 2025
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Location
Shoreline, Washington
Hello,

This is a long explanation and I'll say thanks up front for anyone that can get to the end.
I'm new to the site and I'm looking for information and an opinion or two on an issue I have with the 318 in the truck.
A little about my situation. I bought this 1968 Dodge D200 with a 318, A727 automatic transmission 20+ years ago. I put a couple grand into running gear, replaced the king pins and did a basic tune up and drove it. I used it for projects and fire wood.
The truck started out as a service vehicle for Seattle City Light and has obvious signs of being altered. Based on the modifications that I can see, it's possible that the truck used to be a 383, 4 speed or something like that. The cross frame under the tranny has been cut and filled with a new piece that allowed enough space for the automatic. The area where the clutch rod would have passed through the front wall of the cab has been covered with a plate, the master cylinder has been moved laterally and so on.
Originally I figured Seattle City Light altered this rig during the gas crunch in the 70s but under further investigation, I'm starting to question that theory.
Over the years before I bought it, the engine had some aftermarket items installed like an aluminum Edelbrock performer manifold and an Edelbrock 650. The aluminum manifold finally cracked below the heat riser cross over passage under the carburetor. Eventually, this situation and my own stupidity caused a massive back fire that blew out the exhaust gaskets, the back of the muffler and destroyed the cam gear and thus the timing chain which brings me to my issue at hand.
While removing timing cover, I found some pitting on the timing covers mating surfaces and figured replacing the cover may be in order. During my search online, I found that all the new covers have timing marks cast into the drivers side or right side as you're facing the engine or, no timing marks at all. My existing cover has the timing marks cast into the passenger side or left side as you're facing the engine. Also, when I picked up a new harmonic balancer, I found that the new harmonic balancer is 7 inches in diameter which doesn't match the existing harmonic balancers at 5 inches. It turns out that the existing harmonic balancer is missing the outer ring and has a timing mark that is approximately 90 degrees off, counterclockwise of where the new harmonic balancer's is which may make sense considering that my timing marks on the existing timing cover are on the passenger side.
For now (to keep moving forward) my plan is to add a mark on a new harmonic balancer that matches the existing harmonic balancer and press on. (I know, I know)
My question for you all is; what am I dealing with here? Is this engine the result of almost 60 years of backyard mechanican or do I have an engine that was built this way from the factory for a specific purpose?
The truck has always ran like a champ and always had power to burn.
One other note that may be important, when I found I had to replace the intake manifold and after the massive back fire blew the exhaust gaskets out in a couple locations and the back of the muffler off, I had no choice but to do the exhaust gaskets at the same time. I found the right side exhaust manifold was warped and the surfaces were damaged and too far out of whack to machine so I had to replace that exhaust manifold. After and exhaustive search, (no pun intended) I found someone with a set that matched what I had and it sounded like they may have came off of a bus.
Anyways, if you're still reading this, thanks for any information or opinions on what I may be dealing with and just for what it's worth, I already understand that one man's truck is another mans junk heap.
Thanks
 
backyard mechanican .... but all fixable. If you do not have a factory manual I would recommend you get one, it will help allot.

Is there a inside door info plate still present?
 
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