The Stovebolt Site Forums The Shop Area Engine Shop tranny ID ?

I have a '65 Chevy C10 w/ 230 , 3 on the tree . I've been told ( at a tranny repair shop ) that my tranny is the "shorty " model. It is a (non-synchronized 1st gear) 3 speed . The truck has a one-piece driveshaft . Does anyone know the designation for this tranny ?

yeah, standard Chevy 3 speed! don't know about 'shorty' - in 68 they started using a Saginaw all syncro 3spd that was the same length, fits right in - you have what they used before that for decades, the Muncie or BW, one heavier duty, one standard, but all "corporate" - will have a model number, but better identified by the numbers on it and date codes

Bill

Red58, Is there a link to a page that shows the transmission number codes and how to decipher the date codes? I am trying to determine the year of my non-original SM420, which is in my 54 GMC 100. Thanks.

cojo - very minor differences in the SM420 from 47-67 - see about halfway down here

Bill

i also have a 65 chevy c10 with 230 I-6 and 3 speed on the column (got it for $50 with blown motor has a real nice patina look) i've heard of the non-syncro trannys and was told that you kinda have to double clutch so what do you mean by 1st gear is not syncroed that and like a SM420 4 speed out of a 55 2nd series 3/4 ton be syncroed?
Nate

Thanks Red58! Good site.

The SM420 is not synchroed for 1st and reverse gears, but 2nd-3rd and 3rd-4th are synchroed. You do sometimes need to double clutch even with the SM420 that has synchro rings.

From the Novak site I was able to determine that my SM420 4-speed transmission falls in the year range of 64-67 since my transmission # is 3761930.

Here's the Novak tranny ID info:

1947-1953: No ribs on the case, grooved input shaft instead of neoprene seal. Synchro rings all differ from each other. 1st-2nd synchro ring is bronze. Six digit casting number on the case, usually like "59xxxx".

1954-1963: Same as previous but uses a neoprene input oil seal.

1964-1967: Same as previous except 1st-2nd synchro ring is aluminum and 3rd-4th synchro rings are identical to each other. Seven digit casting number usually like "37xxxxx", "38xxxxx" or "39xxxxx".

One thing that puzzles me is that what I believe to be the date code for my transmission reads "J288" which I would think would decode to October 28, 1968. The Novak site states that the last year the SM420 was built was 1967, so is this statement incorrect or is my interpretation of the date code incorrect?

your date decode souds right - actually that "last year" would be the last year used as standard equipment - could be later manufacture and is a replacement?

Bill