Researching my Industrial 225 block. Metric head bolts, double cam gears, "5R203506" on right side of block just under #6 cyl, "2806830-8" on block behind exhaust manifold and to the right of that and up a little "32941" BH. Looks like red is original paint "Chrysler Industrial" on valve cover. Also, the fan was attached a little higher to an odd looking thermostat/pully, most likely a forklift from Canada? My son has photos on his phone but they didn't come thru to my PC so I'll work on that. Any help will be appreciate.

2806830: RG (198 or 225 depending on crank and rods), '68-'75ish. Same as passenger car/truck/van: forged-steel crankshaft, solid lifters.
-8: Casting pattern ID number
BH: Engineering change ID number
5R: Suggests engine built to standard specifications in 1975
203506: Probably engine-build serial number
32941: Unknown. On blocks cast at Huber (ID'd by "AAWJ" on the manifold side of the block), that location has a 4-digit number which is the casting date. This could be an encoded production date or ???

Metric head bolts: are you real-real sure? Never from the factory. Maybe someone went to great and strange effort to drill and tap every head bolt hole in the block, but it seems unlikely.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I have never heard of metric fasteners on a slant engine. Except on the air injection pump used for emissions, or the late style AC compressor.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

And at that those metric fasteners would only be those that are a part of the smog pump or AC compressor themselves
The bracket bolts that hold them to the engine would still be SAE
Who knows .. there are some size metrics that fit SAE the same as the SAE tools would... 5/16=8mm, 7/16=11mm, 5/8=16mm, 3/4"=19mm, etc maybe he did use metric tools to undo some of it?

While this is true as stated, the thread pitch(es) are still not compatible. I suspect your guess is right.....metric tools were used to remove American thread bolts.

Roger

Yeah. Only referring to wrench head sizes not actual bolt shank diameter or thread pitch size. Most younger people don't even seem to know anything existed besides metric crap.i was just fine working with SAE based stuff, metric does nothing for me besides piss me off.

Saying the system of units and measurements used by »checks notes« the entire freakin' world except for the U.S., Liberia, and "Myanmar" (Burma) is "crap" is…

…a bit of a stretch.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I'm an old man, (Viet Nam Vet) I discovered I'm missing my 11/16" and some screws upstairs. The 17mm is the only one that fit. How you kids say it now? (my bad) Just wondering; is this an industrial block and is it a better candidate for a build? I read someplace it may have more nickel in the casting. Also, it may have had a steel shot pinned crank before the last build at Rettig Bros Machine Shops in Modesto, CA. Looks like a regular crank kit now. My Son has photos but I haven't been able to get them from him. I'll work on that. Thomas

There's nothing such as a Slant-6 block made specifically for industrial applications. It is the same block and internal components as the passenger car engine.
Not necessarily because it was originally used in an industrial application, no. That is not the case. The nickel content of Chrysler's block iron was increased (for all engines) starting in '63. Industrial motors did not get special high-nickel blocks. The heaviest-duty truck engines got shot-peened crankshafts. The industrial engines did not. Remember, industrial service is often quite a bit easier on an engine than car/truck/van service.

If you want to have the crank shot-peened, you certainly can, but there's not much point unless you are building a motor for extreme heavy-duty usage, or just want to be able to say you have a shot-peened crank.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Umm... No it isn't.