Muncie 4 Speed dated after assembly date on an LT-1?

[David H.]

Re: Muncie 4 Speed dated after assembly date on an LT-1?

Mark's info above is correct. The assembly stamp is model year not calendar year. I think there's some confusion between the casting date and assembly stamp.

Jim/Mark

Thanks. What is the casting date of this transmission?

Dave

[Mark F.]

Re: Muncie 4 Speed dated after assembly date on an LT-1?

Jim/Mark Thanks. What is the casting date of this transmission? Dave

Dave,

Excellent question!

I have never seen a tranny case with the grid system dating - and can't seem to find a detailed description with multiple examples of how to interpret them.

What I see in Mick's latest photo is 6 grids on top - all of which appear to have at least one dot in them.
6 grids on the bottom with no dots that I can see

Assuming the top 6 grids represent........Jan Feb Mar Apr May and Jun (left to right) - and I have no idea if that's true or not(?)
I see the following # of dots respectively 3.....4....5....2.....2 and... 1
So, what does that mean? I have no supportable idea.

If it was meant that it was cast the first week in June '70 (because there's clearly 1 dot there in the far right top grid) that's a really long way from Aug '71 - 14 months!

And if that's the case, why do all the previous months other than Feb and Mar have less than the full number of dots representing weeks in that month. Did they leave all the full number of dots for the previous month as they moved into a new casting month run - doesn't look like it from what we see on Mick's.

Having worked in casting plants, I can tell you molds wear out - and tiny little dots like that (actually, the are depressions in the mold or core that create a bulge when the hot metal fills it) can get misaligned and not imprint as deeply they should.

Beats the heck 'outta me why they didn't use something much simpler and more reliable like "Model Year - Month - Day" or some variation of that...just like used on most of GM's casting as John indicates. Maybe casting dates on the tail piece and side cover might provide more insight(?) - assuming the tranny has not been messed with.

The mystery continues hopefully someone who knows what they are talking about (and that ain't me) can help Mick!

[Gary B.]

Re: Muncie 4 Speed dated after assembly date on an LT-1?

I've been told the upper left box is July, the start of the final half of the year. Each dot represents the week. Looking at the upper row of boxes, the final box is December and a single dot is shown..... So first week of December. Coincides with a December 13th build.
Gary B

[Mark F.]

Re: Muncie 4 Speed dated after assembly date on an LT-1?

Good deal, Gary - I would have never figured that out, but I guess Muncie wanted to keep things disguised, eh?

[David H.]

Re: Muncie 4 Speed dated after assembly date on an LT-1?

I've been told the upper left box is July, the start of the final half of the year. Each dot represents the week. Looking at the upper row of boxes, the final box is December and a single dot is shown..... So first week of December. Coincides with a December 13th build.
Gary B

Gary

Thanks

Dave

[Patrick B.]

Re: Muncie 4 Speed dated after assembly date on an LT-1?

Patrick

Believe year in GM castings refers to calendar year - not model year. Believe this casting is from 1971.

John Hinckley article originally from Corvette Enthusiast.

cast_codes.pdf (camaros.org)

Dave

The discussion about the Casting Date of this transmission case was only about months and weeks, and June and July were months included in the speculation about how to interpret the month grid. It is not clear that the calendar year of casting is even coded on a Muncie case. Does anyone know where to look for it? The stamping identifies only the model year. The stampings on this case look very original and indicate an August 13, 1970 build date which is in the 1971 model year production time.

[Mick D.]

Re: Muncie 4 Speed dated after assembly date on an LT-1?

Thanks for your notes Patrick - I will try and get some better pictures, but it is nice to know that the transmission might pre-date the build date (May 5th 1971). Maybe it is actually original.

[James G.]

Re: Muncie 4 Speed dated after assembly date on an LT-1?

Patrick is correct the trans assembly stamps are model year not calendar year.
My 71 LT1 trans assembly stamp is P1E25A
My 69 Z muncie was P9R18 assembled October 18 of 1968 for 1969 Model year.

[Mick D.]

Re: Muncie 4 Speed dated after assembly date on an LT-1?

Thanks Patrick - Good to know this! I like your 1971 LT-1 Album.

Looks like we have the same year, color and model, basically identical except for the top!

Patrick is correct the trans assembly stamps are model year not calendar year.
My 71 LT1 trans assembly stamp is P1E25A
My 69 Z muncie was P9R18 assembled October 18 of 1968 for 1969 Model year.

[James G.]

Re: Muncie 4 Speed dated after assembly date on an LT-1?

Your car is the one which was for sale in Hilton Head SC. I live in upstate SC, I remember the car being for sale.

[Mick D.]

Re: Muncie 4 Speed dated after assembly date on an LT-1?

Hey James, thats correct.

Was from Hilton Head Island, made it 2700 miles unscathed. It looked better in person even than in the pictures.