The Stovebolt Site Forums The Shop Area Driveline Correct 4 speed for a 1958 1/2 ton 283ci

Finally completely done restoring my 1958 Chevy 1/2 ton, EXCEPT for the shifter....changed from original 3 speed to a 4 speed Saginaw and am now hostage to the supplier of the 4 speed shifter needed to make it work. I am not hopeful I will ever get the shifter as the company appears to be really struggling, so I am now considering pulling the Saginaw and replacing with an original, correct 4 speed and shifter. My question is, what is the correct original four speed model used in these trucks?

Thx!

the "correct" 4 speed would be the SM420 seen here, but why would you want to use a granny geared trans?
find yourself an original overdrive 3 speed and stick to column shifting

Bill

Really trying to go 4 speed but I take your point...what would the model number/name of the original three speed OD tranny be?

An SM 318 would have been the original 3 speed, but you'd need all the column shift linkage to make it work properly. A floor shift conversion would put you in the same situation as the Saginaw 4 speed.

There are dozens of Saginaw 4 speed shifters available on ebay- - - -mid-1970's Vega cars ran them, along with Oldsmobile and Pontiac pony cars of similar vintage. I mentioned this the last time you brought the subject up, also, and even found the Ebay listings for you. This time it's your turn to search.
Jerry

Thank you - I did not ignore your advice and did search ebay. I didn't have enough confidence that anything I found there would simply bolt on without modification (I may well be wrong) so was pursuing alternative paths first. A logical one would be to use the original type 4 speed and the original type shifter for the truck. Other than a slight difference in steering column (shift mounting point)and the transmission cover, I know of no other differences between the 3 and 4 speed equipped trucks, so I don't think I'd be in the same place as I am now. I have the three speed linkage and the original 3 speed non-OD transmission, so that also remains an option. 3 speed with OD was not a 58 option, so I was inquiring as to its model number as a third option.

Wasn't there an optional 3-speed overdrive transmission in 1958 (passenger and 1/2 ton truck)?
M319 (Muncie 319)?

Like I used to tell my students- - - -you can expend a lot of time and energy making up excuses why something won't work, or use a fraction of that effort making things go your way. Your choice.
Jerry

I believe the 3sp overdrive was an SM319. It will bolt in place of the original 3 speed and use the original linkage. You may have to change the cover on the side of the transmission with the original one.

there was definitely an optional OD trans from 55 on, see accessory list here - the SM319 as Tim sez

Bill

The original truck type 4 speed (SM420) is shorter and uses a completely different driveshaft from the 3 speed, 3 speed overdrive, and the passenger car 4 speed.
The SM319 OD transmission was available in both cars and trucks from 55 through 65. With a Saganaw version from 66-69.
Fred

First let me say that I am very grateful for the assistance I have received over the years from the members of Stovebolt. You guys have allowed a novice like me completely tear down every nut and bolt of a pickup and completely restore it to its original glory. I couldn't have done it without you.

I will say that occasionally the condescension in some replies is dripping - I can handle it (I KNOW I don't know things), but I would imagine some might be intimidated or put off by it.

Finally, with regard to the availability of overdrive in 1958 and 1959 trucks, the research I did specifically indicated OD was not available in 1958 and 1959 chevy pickups. CLEARLY, I may be wrong, but my source is "Chevrolet Pickups 1946-1972" by John Gunnell. On page 50, "Overdrive was no longer avaialble [in 1958], but all other transmissions previously offered were back again." On page 52, "Transmission offerings [in 1959] were the same as in 1958. Despite the new emphasis on economy, overdrive was not available, even though it had been a Chevrolet option up to 1957."

Thanks again.

no offense gobolt, to you or Gunnell, but the RPO315 OD trans is mentioned in both the 58 and 59 resto paks from GM - odd that the OD trans would be mentioned in factory documentation but left languishing on the shelf for 2 years of it's 10 year run .... might just be that Gunnell didn't find anyplace it was specifically mentioned in sales literature

Bill

None taken, always happy to learn - I just wanted to indicate that I didn't make this up. Also, 1958 salesman's guide (an early original version, pre cameo discontinuance / fleetside release) that I own shows only options as hydro, 3 or 4 speed (no OD option) for any version of the pickup, for what that's worth.

There are a few mistakes/misstatements/errors in Gunnel's books (on Chevrolet Truck History and in GMC History).

1958 truck specifications manual - 3 speed conventional and overdrive are listed

1959 truck specifications manual - 3 speed conventional and overdrive are listed

The GM Chevrolet Specifications documents are more reliable.

Not to confuse anyone with facts but I just rebuilt one with a 58 date code.
Fred

The GM Truck Specification Packets for 1958 and 1959 are very incomplete and missing lots of pages when conpaired to the 1957 packet.

My 1958 and 1959 Truck Data Book's do not list OD as an option for the 3000 series truck, but the 1959 book does have them listed for the El Camino's (which were part of the truck group).

The serial number page in the specification packet should not be used as proof they were actually installed in the trucks, those pages seemed to be carryovers from the previous year in many cases and are there to inform where to look for a serial number on the different transmissions, not what they were installed in.

Fred, the OD transmissions were the same for the cars and trucks, so there will be OD transmissions with 58/59 date codes. The question is can anyone prove they were installed at the factory in the 1958/59 3100 trucks?

Mike B

Have you looked into T & F shifters? I have one in my 56 3100 and love it!

http://www.hotrodscustomstuff.com/OLD_SITE/TFshifter.html

Mike B

I have not but will now - much appreciated, Mike!

Mike, the transmissions were not exactly the same for cars and trucks. The trans cases on cars were drilled for 4 bolts to be installed into the bell housing from the trans side. On the trucks the lower mount holes were threaded on the transmission side whereby the bolts were installed from inside the bellhousing. The side covers are different and 58 up rear housings also had a pad for a rear mount even if the mount was not used on trucks.
From what I have seen with regard to date codes, the later date code would be installed in the next year - for instance a May date code would likely be installed in a 57 and a July or Aug date code would likely be installed in a 58.
With all the mixing and matching that has taken place over the last 50 or 60 years, it would be extremely hard to prove what the vehicle had in it originally unless someone had a completely original vehicle that hadn't ever been touched.
To me, a trans with a truck case, rear mount, and a late 57 or 58 date code would have likely been installed in a 58 truck.
Fred

Fred,

Thanks for the info on the differences between car and truck!

My 58/59 Sales Litterature, Truck Data Books and my 29-59 Parts Book only lists OD for the 55-57 1/2 ton trucks.

The Parts Book even has a foot note for Non-OD 3-speed transmission cases used on "55-59 COMM w/3-speed (cast 3845122), p/n 3707166" to "use through bolts with nuts at two transmission to clutch housing locations". So it looks like the passenger car case was used as the replacement for the trucks.

58/59 date codes could have been warranty/replacement cases.

Mike B

I guess the point that has been missed is the poster was adamant that there was no OD transmission offered in his year truck.
Even if it was the case, why should that matter? If he is building an exact numbers matching 1000 point show truck he wouldn't have a passenger car 4 speed in it. Any 3 speed overdrive from 55 through 65 will bolt right in and no one would care.
Many of the OD units that I rebuild are passenger car units.
Of those most are installed in trucks with bolts as Mike
mentioned.

Fred

Fred, you are appsolutely correct, only a hand full of people would ever look at that truck and say "wow, you have the wrong transmission"...lol. Bolt it in and have fun!

Mike B