The Stovebolt Site Forums The Shop Area Driveline My 1953 Chevrolet Panel Truck 1/2 Ton 3100

This was on the left side (drivers side) of my transmission. a 7 GM 591615 to the right side of the 7 looks like H278 . can anyone decode this please ????

Here is a pic.

A bit of checking using the GM Partswiki link found in a "sticky" post towards the top of the General Truck Talk forum shows that the "casting" number 591615 represents the "main case" for all 1948-54 Commercial (truck) 3 speed transmissions.

The date casting code "H278" can't be directly identified from info I was able to search for your "1953 3100" here: https://www.gm.com/content/dam/comp...evrolet-trucks/1953-Chevrolet-Truck.pdf.

According to that document, you first need to locate the actual transmission "serial number" which is stamped in the left side machined flat side where the shifter plate mounts. You will need to clean the flat surface just above the "H278" code and look for a set of stamped letters/numbers.

Once you have those numbers, you can refer back to the '53 Truck Specification document linked above to decode what the serial number can tell you (ie; Plant and date codes).

Helpful???

Could the 8 in H278 be a 3 instead? I enlarged the picture, but can't tell. If it was, H273 would be August 27, 1953.

Bill,

You could very well be right. That date would coincide with the '53 model year he has reported.

My suggestion would be to hit it with a stiff wire brush on the casting code and that machined flat above to see if a it is a "3" and what the actual "serial number" is.

Thanks for a little more insight.

Good morning guys, sorry this took so long to get back at, but the is a H273 and i got the serial number and it looks to me like its : 3686832 GM.

Morning back at you

Great you have confirmed the "casting date code" to end in a "3".

That helps confirm it's a '53 model year unit. To be specific, it decodes as:

H = August
27 = 27th day of August
3 = 1953

The second number you provided "3686832 GM" isn't a "serial number". It's actual the casting/part number for the transmission shifter side plate unit.

According to the Tech Service Bulletin (TSB) # 249 (found at the beginning of the above linked 1953 Chevrolet Info Kit) the serial number for your transmission should be found on the small machined flat at the upper rear section of the main case, just behind the edge of the side shifter cover. See a screen grab of your original pic with an arrow pointing to the spot where the serial number should be.

More details from the TSB# 249 show the serial number should (for your 3 speed) begin with the letter "M", followed by 1 or 2 numbers to indicate the month and finally 2 numbers to indicate the day of the month (see the other attached screenshot).

Since your main case casting number and date already confirm you have a 1953 3 speed, up to you if you want to go further to try and clean that machined pad and verify by serial number what you have.

Let us know what you decide/figure out.

Dan

Gdads51 ,Thank You so much for all that information and screen shots. i will get that other number/letter combo either fri. or sat. and let you know. Have a good evening and Thanks again.