My 6 year quest for a CX coded THM400 just ended

[nuch_ss396]

Hi everyone,

Recently, I posted a topic here about the special Turbo400
transmissions used in the 396/375hp cars, COPO and other
super cars, etc.. These were CX coded. Over the weekend,
my 6 year quest for one of these babies ended successfully.


My original CX went bye-bye a long time ago (before I owned
the car). I had been looking for another one it seems forever.

A few weeks ago, there was an eBay auction for a complete,
untouched L/78 engine out of a 69 Nova. The seller also
mentioned it came with an M40 transmission. Seems it was
removed in 1974 due to the gas crisis - remember that?

So, I contacted the seller to get all the particulars. You
know, casting numbers, dates, and the code on the THM400.
To my shock, I was told that the code was a CX. When I
came to ( passed-out ), I knew what I had to do. Much to
my dismay, the seller would not break the THM400 away from
the L/78 auction.

Also, after he found all of the casting number & date codes,
he did not update his auction. The auction did not meet
the reserve price set, so it ended. I contacted the seller,
and ended up buying it all. Mostly, because he still would
not split up the items.

So, I have a complete "JL" coded L/78 engine and the CX
coded THM400. All I wanted was the CX, so the L/78 will go
up for auction. The main reason for this post is that I
found a slight date issue that I would like to resolve.
This engine has a assembly code of T02??JL. The ?? denote
two numbers that cannot be read. I have looked very close.
The heads are late January dates, the exhaust manifolds are
mid February dates, the intake is an early January date and
the distributor is a late December (68) date. Also, the
water pump is an early January date as well. The odd thing
is that the 3955272 block is an H-13-8 date. Almost six
months before the assembly date of the engine.

What do you guys think about that? I have every confidence
that this engine is the "real deal". Any thoughts? Images
below:

Steve

[YENKO DEUCE REGISTRY]

I don't think the block is too early for that build date. In talking with jeff of Dated Components, 6 months is well within the timeframe - he has seen as much a 1 year gap to as little as 2 days.

[mockingbird812]

Steve,

I resized the 1st picture for you - will do the others in a few. Nice motor. Good luck!:

[mockingbird812]

Looks like your pix are coming thru now. Were'nt the first time I looked at your listing.

[Chevy454]

Did you happen to get the converter?

[ANDY M]

I could use one of those CX M40s. Hope I get as lucky as you.
You GO

[Enoch]

Steve, from the picture that looks like the real deal. The block has been lightly decked and the month date #'s were not as deep as the others that's why you cant read them. But just at a quick glance that's the original stamp. I also have seen a few block casting and build dates stretch out that long, although they are few and far between.

[nuch_ss396]

[ QUOTE ]
I could use one of those CX M40s. Hope I get as lucky as you.
You GO

[/ QUOTE ]

Andy,

I ran across another one last year by accident. The seller
started with a $1,000.00 price, then up to $2,000.00, then
all the way up to $4,000.00 ! I bugged-out somewhere along
the way. Too much for a transmission.

Steve

[nuch_ss396]

[ QUOTE ]
Did you happen to get the converter?

[/ QUOTE ]

No 6-point converter! The seller told me he used it for
another project along the way.

I have been told that they are still available from GM. Anybody know for sure?

And, while we are on the converter subject, other than the
six mounting points ( bolts ), is there anything special
about that converter?

Steve

[nuch_ss396]

I want to thank everyone for the verification you've given
me on the L/78 & CX THM400.

OK, now that it appears that I have a true JL coded L/78,
my attention turns to rebuilding the CX THM400. It has
been sitting for almost 30 years and I want to have a good,
qualified shop rebuild it. I would be looking for a shop
that understands what the CX is and how to build it as it
came stock. Also, I will need the 6 mount point converter
for the CX. Are they still available from GM?

Can anyone recommend a good person or shop to rebuild the
CX THM400? As they say, you only get one chance.......

Steve