Look at the right side of the main case. You will see a cast in date code on the case body, a standard 4 letter/digit combo that indicates the date code.

Just above that on a machined pad, there will be the last part of the VIN stamped into the smooth surface. It should look just like the VIN stamped onto the engine block.

The picture below is my 72 GT M-13. Notice the VIN stamped into the smooth surface, and just below, cast into the case is the date code. In my case, D122. That translates to April (D), 12, 1972. My car was built the first week of May 72, and the VIN matches, so it's the original to the car.

Hope that helps. :)

If you find a Buildsheet in the car , it would have RM coded in the transmission designation box.
M13 also came behind 69 & 70 Ram3 engines and 70 455HO engines.
They are tuff units.

Fantastic!

Nice to have all the original parts if you decide to keep the car stock.

I built a mild stock 455 for my 72 GT, and simply set the original 350 on a stand in the corner of the shop as others have mentioned. I've learned that I enjoy the car much more this way.

Should I ever decide to sell the car, I would simply put the original 350 back in, and sell it that way. Most guys will want to install their own drivetrains, so original engines really never go back into a car once they're out.

That being said, put in what you want for now to enjoy, but keep the original in the corner for the day you decide to sell, then return it to original condition. Let the next guy decide what he wants to do with it then.

:)

If you could happen to find a bare 400 block on the cheap side, you could use everything from the spare 350 - and have the crank rods pistons balanced.
Or a 400 short block on the cheap.

400 pistons are about the cheapest ones off the shelf.
350 oversize pistons are usually custom ordered these days $.

Maybe even a 455 short block ,, if the #94 heads are around 95cc combustion chambers

I wouldn't want to throw that kind of money at a 350 2bbl

"Almost" everything is interchangeable on Pontiac engines from 326 through 455.
421, 428, 455 use bigger crankshafts

Phoenix, I can understand your hesitation with budget constraints, but as far as your skills? If you have successfully built a SBC, you can certainly build a Pontiac. Sure, they're different, but they're actually extremely straight forward with a ton of interchangeable parts (as mentioned).

Another thought...

I love to find a 'good used' engine when possible. Someone will have a good running 400 they pulled to drop in a 455, or perhaps a wrecked car with a good running engine. If you can find one of those, I think you'll come in well under your stated budget. I've done this very thing for years when I need a 'place holder' and just want to drive the car.

You're well on your way with the brakes done and original engine/trans pulled. Finish up the fuel system rebuild, meanwhile, see if you can't find a good running 400 or the like for half the price of your estimated rebuild cost. Cleanup the Muncie, drop it back in, and go spin the rear tires! It's one of the fastest, most cost effective ways to get your car back on the road where it's always more fun.

To quote Frieberger from Roadkill, "Don't get it right, just get it running!"

There will be plenty of time to rebuild that 350 later as funds become available, but you'll be thousands of miles and smiles down the road by then.

:cool2:

Thanks for your help figuring this out. You guys have been so helpful. Here are some 400's I have found that are in reasonable distance.. Do you guys have any thoughts on these...What questions to ask, etc?

https://annapolis.craigslist.org/pts...675788752.html

https://pittsburgh.craigslist.org/pt...674541487.html

https://www.ebay.com/itm/13468296078...Bk9SR_zn6P_sYg

https://www.ebay.com/itm/13471498017...Bk9SR7jllYDtYg

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It wouldn't hurt to document them with some clearer pictures.
I can make out the 19 - which should be paint code for Black.
But I wouldn't put them back on it. (personal opinion / preference)

The 69 engine & tranny deal isn't real bad..
The others are really high.
73 TA only came with 455's and 4bbl's - you will have to crunch the numbers and letters on any prospect to authenticate - like you did on your blocks and heads.
Very few folks actually know what they have or have not.

All you need is a good 400 block.
Or maybe even check with a company like Jasper on a 400 short block already assembled.
You would have to eat the core charge though.

The best deals on full engines are usually from 68-70 Grand Prix 400
You get really good heads and 4 bbl intake/carb

I totally concur with the 400/455 sentiment from Mister Pontiac and BVZ if you have to rebuild the original 350 anyway. You might as well invest the same $$$ into a bigger engine, which will not hurt the value of an original 350 GT-37 one bit...most likely add value. Just store the original engine in the garage and it stays with the car if you ever sell it down the road. You can still find the early (pre '75) 400's relatively easy and affordably. Like BVZ mentioned, that '69 400 2-bbl engine looks like a great candidate.

I have a '70 Lemans 4-dr post sedan that I swapped out the original 350 for a 455 from a '70 Bonniville. I found the 455 for $500. It was the small valve 360 hp variant and I kept the small valve heads and log exhaust manifolds and it made 390 hp at 512 lbft torque on the dyno with a little bigger cam (Summit 2802) than stock. I'm so glad I did as the car is a blast to drive.

You'll be glad you made the upgrade to more cubes for the same costs.

Dennis

The 69 400 engine could be had for $500 without the transmission.

STORY ON THE ENGINE GOES LIKE THIS: It ran 12 years ago when the guy bought a 68 firebird with this engine in it. The guy he bought it from had started building the Firebird back in the 80's but never got it on the road. The current owner ran it for just a few minutes just to make sure it ran and said it sounded ok even though it was loud with no exhaust. Thinks it's from a B body car originally. Current owner never finished the car and then junked the car and moved the 400 into his garage for the past 4 yrs. Now he needs the space and wants to sell.

I wish it wasn't 4 1/2 hrs away....

https://pittsburgh.craigslist.org/pt...674541487.html

Couple thoughts of mine, Phoenix...

I would preserve the markings on the firewall if it were me (I did on my 67 GTO), but as others have said, personal preference. I don't know if it's make or break to the next guy. I would want them, others could care less.

That 400 is interesting. To me, $500 is fair for a complete engine. Being 1969, it could still be a higher compression engine. No way to know unless the guy can get you the head numbers, but before I did a 4.5 hour drive, I'd want to know what exactly it is. I'd ask for the block code and all the date codes too, but he may or may not be willing to help.

In this day and age, if you're planning a lot of driving, I'd look for a 71-74 engine. If it's still untouched, you would get a low compression (pump gas friendly) hardened valve seat version, and the stronger (relatively speaking) block vs 75 & up. Additionally, a 71-74 is probably less desirable to most guys than the 70 and earlier versions. But for your purposes, absolutely perfect. Drop it in and go. That would be my vote. I'd keep looking.

Keep up the good work, and keep after it! While you've got the project momentum, don't stop until it's running and driving again. Nothing more motivating than that!

:)

That would be a fairly 'correct' 71 400 for you (YS would have been from an automatic car, but regardless), $1400 is too high for a core short block, IMO.

If it was a complete engine, especially with the #96 heads, then I would say you might have something.

Personally, I would pass on this one too.

But since you have a lot of other things to do on the car, keep at it. The right engine will pop up. Keep an eye on the classified's here on the forums too. Someone up in your neck of the woods may have just what you need.

:)