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[Motherfrog402]

Originally Posted by Titomars

...I wonder if this is a rebuilders stamping and not GM's

The only thing that leads me to believe that it is not is the location of the pad...if it were a V8, then I could think that a machinist machined the deck and wiped out the number, but the 292 pad is in an area that wouldn't be machined, plus the lettering looks like the GM stamps I've seen on my other V8 engines. No, I almost wonder if that "P" is for the P-Series chassis vehicles. Everything I've read up on says that the "F" means it was built in Flint.

[Motherfrog402]

Originally Posted by Titomars

GM like the all of the Big 4 back then shut down all assembly plants in late July for retooling for the next model year. Next year production started in late August. Officially the model year ran from September to August. So take 74 for example. production started in late August of 73 with a debut of Sept. 73 and ran till the 3rd week in July 74 when the plants close for 3 to 4 weeks to retool for the 75 run and so on. Ever wonder why you never see an August production date on a car or damn few of them?
So a 08/73 built engine could be perfectly correct in a 12/73 built vehicle as a 74 but a 9 month old engine would not. even in 73/74 there were federal emissions and safety standards that had to be met. and an engine built for the 73 model would not be technically compliant for 74. Now GM could erase the data stamp and reconfigure it to 74 specs and re-stamp it but knowing how GM did things back then, They would have scraped the engine. It was too expensive and a legal issue. So they either generally melted it down or donated such things to school/college auto shops around the country for teaching aides only. Never to be put on the road.

True, but remember that pre-'79 trucks over 6000lbs GVWR were emissions exempt, treated as heavy-duty vehicles, so couldn't the '73 engine carry over with no repercussions? BTW, I'm not saying that I believe that they used a nine-month old engine, but I'm at a loss to explain this. This is more AMCish than GM's style of doing business.

[Motherfrog402]

Another explanation might be that the engine was replaced by the original owner. He owned an auto repair shop here in Nampa. Possibly the original engine blew and he had another on hand?

[Titomars]

By the way in an earlier question you asked, I get my parts from a few places.
LMC http://www.lmctruck.com/
Classic Industries http://www.classicindustries.com/
Classic Parts http://www.classicparts.com/
I also get stuff from Summit, Ebay, Craigs List, etc.
Personally I do a lot of business with Classic Parts They have some OEM stuff too.

[Titomars]

Originally Posted by Motherfrog402

Another explanation might be that the engine was replaced by the original owner. He owned an auto repair shop here in Nampa. Possibly the original engine blew and he had another on hand?

I just don't see GM using an engine in a carry over mode, exempt or otherwise. It is just not how they did things. Besides the engine lacks its correct 3 letter code. Also in California the exempt status was 8500 lbs. My best guess is it is a re-builders stamp. about the only way you could verify or deny it would be open it up.
Even though your 292 did not come with certain smog equipment like AIR injection or EGR, it still had some emissions equipment that required model year certification. A spark control system and a thermostatic air cleaner also a closed PCV system and maybe Evaporative system. But I'd have to check on that one though.

[Titomars]

Originally Posted by Motherfrog402

The only thing that leads me to believe that it is not is the location of the pad...if it were a V8, then I could think that a machinist machined the deck and wiped out the number, but the 292 pad is in an area that wouldn't be machined, plus the lettering looks like the GM stamps I've seen on my other V8 engines. No, I almost wonder if that "P" is for the P-Series chassis vehicles. Everything I've read up on says that the "F" means it was built in Flint.

"P" chassis got engines with the "T" as the first letter also. I checked my factory manuals all gas light truck engines from 73 to 78 for domestic use began with "T". And we both know 292's were not offered in any other line but trucks.
What it could be is a factory crate engine. The GM Targetmaster line had a 292. But its been 30+ years and I don't remember the codes for them. The only problem with that theory is Targetmaster engines were black not Chevy orange. Yours does not look like it was ever black.

[Motherfrog402]

No it is definitely Chevy Orange.

[Motherfrog402]

Last night I was looking at eBay and came across the correct 7044026 Rochester MV. It's in need of a rebuild, so I bought a rebuild kit for it, as well as a choke pull-off and linkage.

[Motherfrog402]

Quick question...I'm trying to figure out what gear ratio I have. The Service Parts Identification decal doesn't list it. Short of popping the cover, which I really don't want to do at the moment, is there an axle code on the 14-bolt itself? If so, is there a list of axle codes somewhere? I've looked and couldn't find anything.

Thanks.

[Motherfrog402]

I did find this:

10.5-inch with case number 6258336:
• The 10.5-inch 14-bolt differential, with the case number 6258336, is found is found on 1/2-ton and 3/4-ton vehicles manufactured by GM 1973 and later. This differential is available in three gear ratios: 3.42:1, 3.73:1 and 4.10:1. This differential is stock supplied on a variety of GM vehicles containing 1/2-ton and 3/4 engine designs. This differential is not restricted to specific product lines or vehicle types.

10.5-inch with case number 6258340:
• The 10.5-inch 14-bolt differential, with the case number 6258340, is installed on larger 1/2-ton and 3/4-ton vehicles manufactured by GM 1973 and later. This differential is available in three gear ratios---4.56:1, 4.88:1 and 5.13:1. This differential is stock supplied on a variety of GM vehicles lines with a rear differential that turns significantly more times at the rear end than does the 4.10:1 and lower ratio line of differentials.

[Titomars]

Originally Posted by Motherfrog402

Quick question...I'm trying to figure out what gear ratio I have. The Service Parts Identification decal doesn't list it. Short of popping the cover, which I really don't want to do at the moment, is there an axle code on the 14-bolt itself? If so, is there a list of axle codes somewhere? I've looked and couldn't find anything.

Thanks.

There is stamped into the RH axle tube a set of codes that gives original gear ratio and if its posi or not also build date and plant. For corporate axles on 20 and 30 series it is about 6 to 8 inches from the carrier casting and facing the bed floor or up. What you want is the first 3 letter code which will tell you what it had/have. For a Dana it is in the same location but the 3 letter code is after Dana's part number. Assuming the gears were not changed by a PO of course.

[Motherfrog402]

What I found was "G3414" and nothing else, other than the letter J, right by the pumpkin.

[Motherfrog402]

Found it, "KJJ"

[Titomars]

Originally Posted by Motherfrog402

Found it, "KJJ"

KJJ = 4:10 ratio with posi-track, 1978 C20

[Motherfrog402]

Just '78? Jesus, this truck is one hell of an anomaly.

[Hankster]

Following!

[Titomars]

Originally Posted by Motherfrog402

Just '78? Jesus, this truck is one hell of an anomaly.

No, I only have books to 78. 78 was the first year for the code by my books. It may carry up for many years. I probably should look into getting later books ;

[Motherfrog402]

Okay, next question, I take it the G3414 is the date code? To what does it translate?

[Titomars]

Originally Posted by Motherfrog402

Okay, next question, I take it the G3414 is the date code? To what does it translate?

I can tell you what some of it means. "G" stands for the plant it was built at which is listed as "gear & Axle" which I think is the Flint Mi. plant. "341" is the actual date code. The "4" is the shift code.

[Motherfrog402]

Originally Posted by Titomars

I can tell you what some of it means. "G" stands for the plant it was built at which is listed as "gear & Axle" which I think is the Flint Mi. plant. "341" is the actual date code. The "4" is the shift code.

341, is that the ordinal date? April 1st, 1973 (3/4/1) was a Sunday; January 10th 1973 (3/41) was a Saturday; Friday December 7th, 1973 (341).

[Titomars]

Originally Posted by Motherfrog402

341, is that a Julian date? April 1st, 1973 (3/4/1) was a Sunday; January 10th 1973 (3/41) was a Saturday; Friday December 7th, 1973 was 341.

Yes, they used Julian dates. It is Dec 7th 1973 which would fit your rig of a 12/73 assembly date.
Also I was in my book again and found KJJ listed in 74 and 75 on a C20 but in 74 and 75 it is non posi. Sorry not sure how I missed it the first time through. I think I went back and checked 77 and then 76 saw none listed and assumed. My bad

[Motherfrog402]

I figured it wouldn't be posi, given it's such a base model truck. At least it has the SM465.

[73Super8]

Sweet find! Looks like you got a good deal.

[Motherfrog402]

I went to the local pick 'n pull today, The Jalopy Jungle. Got my list of where the mid-70's Chevy/GMC trucks were, took my toolbox and went hunting. I got a coolant overflow bottle from a '77 C10, a heater control unit from a '74 C10 and a glove box liner from a '75 GMC.....$24 for the lot.

I don't know which "engineer" designed the glove box liner, but he ought to be castrated, hanged and shot. What a stupid design, guaranteed to eventually split along the seam that folds. I also found out that the '77 overflow bottle's holes only match two of the three holes on mine...the top hole is about 1" lower...everything else seems to match. It beats the brittle and cracked bottle that was on there.

[El Dorado Jim]

Originally Posted by Motherfrog402

I spent all of today recovering from yesterday's endeavors. My back and knees just aren't what they used to be.

Tomorrow's task will be to clean all the crap out of the bed that the PO left me. Brooke has told me that I can spend $300 per month on it, so a new Rochester MV and engine gaskets are first up in March; April will give it a new windshield; May/June's budget will get new dash and engine harnesses; July/August will get new tires and Renée will be able to start driving it at the beginning of the school year.

I'm still deciding on whether to stick with the 8.75-16.5 tires or jump up to the 9.50-16.5 tires.....ideas?

Eventually, once Renée is in college, the truck goes back to me and will get the restoration treatment. I'd like to turn it into a Camper Special (which is why I was toying with the 9.50-16.5 tire choice) and upgrade the interior to a Cheyenne Super. 454 will replace the 292. Oh yeah, color will be changed to Blue too.

By the way, who sells authentic restoration parts for our rigs? I'm not impressed with LMC at all, since they pawn the '77 grille for the '74. Particularly, I'd like to get the Cheyenne Super trim work.

This is what I'd eventually like mine to look like:

http://www.truckandcarshop.com/images/logo.png I buy most of my parts here,they have very good repo parts,not sure if they have 73-74 grills or not