The Stovebolt Site Forums The Shop Area Driveline Identify 3 speed manual transmission

Yep, been told too many stories about what this tranny could be. It is in my 1961 C20 with a 1957 283. View the pics and please tell me any info on what this is. Was there really only one basic 3 speed back in the day??? I know this could be from the 50's or much newer.

What you have is the garden variety SM 318 3 speed column shift transmission. The K 8 60 = Nov 8th 1960. There was a 3 speed overdrive available, a Warner Heavy Duty 3 speed (rare), an SM420 4 speed, and I believe a Powerglide also. Basically the same 3 speed in trucks from 55 through about 63 with the long tail housing, from 64 to 67 (in some models) had same trans with a short tail housing.
Fred

Thank you Fred, that explains my confusion. I looked at dozens of google photos and E-bay listings trying to sort that out.

I have one out of a 55.2, is it a good model 3 speed tranny? I also have a 3 speed close ratio from a 1957 150 2 door hardtop with 283 two four barrel factory Duntov cam. Question can I put close ratio gears in the SM 318 tranny? Doc.

Nope, that close ratio trans is a Borg-Warner, not a GM corporate box (Muncie). Virtually nothing interchanges, but the B-W box is worth about 3 times what a SM-318 is to the right buyer.
Jerry

Thanks Jerry. Ed

Jerry,
I disagree, you may be thinking about the Warner T-10 4 speed. There are three gear ratio options available for the Muncie (4 bolt side cover) case. The standard (55 up- many cars and trucks) has a 2.94 first gear and a 1.68 second. The intermediate -sometimes called HD, (348 engines, Pontiac, 62 up Corvette) has a 2.47 first gear and a 1.53 second. The Corvette close ratio (56-61 Corvette/57 car w/performance engine) has a 2.20 first and a 1.68 second.
I currently have a 57 Corvette transmission with the correct gears and rear housing with the threaded bosses for the shifter and rear mount.
I also build the SM319 overdrive transmissions with the intermediate gear sets for trucks using the 4.57 rear gears. The OD does not come with this gear set but makes for a better driver.
I wouldn't recommend the close ratio gear set unless you have a fairly deep set of rear gears or you will be replacing clutches frequently.
Fred

The Warner T-10 was built by adding an idler and a reverse gear to the rear housing of the T-85 heavy duty 3 speed, back in about 1957. A lot of Pontiac factory race cars ran the T-85, as it was much stronger than anything Muncie was producing at the time. That made room for an extra forward speed in the main box. I remember the advertising campaign Chevy kicked off when that transmission became an extra-cost option for the Corvette and a few other factory hotrods. It came along about the same time as the Rochester fuel injection system on the then "new for 1957" 283 engine. Chevy built a few fuel injected "210" 2-door sedans with the T-10 for drag racing- - - -lightweight low-bucks bodies with the Corvette performance package. The supercharged Ford 312's ate their lunch at the drag strips anyway!
Jerry