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03-13-2016, 03:08 PM
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#1 |
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Registered User
Join Date: Aug 2010
Location: Southern CA
Posts: 1,605
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Transmission ID?
I'm not familiar with these two models, can anyone ID them?
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03-13-2016, 03:10 PM
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#2 |
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Registered User
Join Date: Aug 2010
Location: Southern CA
Posts: 1,605
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Re: Transmission ID?
First one
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03-13-2016, 03:13 PM
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#3 |
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Registered User
Join Date: Aug 2010
Location: Southern CA
Posts: 1,605
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Re: Transmission ID?
Second one
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03-13-2016, 03:41 PM
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#4 |
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Registered User
Join Date: Sep 2008
Location: San Carlos, Ca.
Posts: 3,048
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Re: Transmission ID?
Pretty sure that the first one is an SM 465 by the reinforcing ribs in the case casting and the second is an SM 420 by the lack of the reinforcing ribs. Not 100% as Im not totally familiar with either of these.
__________________
Chris '63 k15 long step Vortec 7.4 - L29 Blackbear tune, Five 0 Motorsports injectors, Chris Straub Cam, NV4500, divorced 205  52" front and 63" rear spring swap D44 / 14bff - disc axles Milemarker 9K and 10.5K hydraulic winches 63" & B52 Spring Install http://67-72chevytrucks.com/vboard/s...ng+swap+thread NV4500 Reverse Build Thread http://67-72chevytrucks.com/vboard/s...=reverse+build L29 - 7.4 Vortec Build http://67-72chevytrucks.com/vboard/s...&highlight=L29 |
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03-13-2016, 06:28 PM
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#5 |
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Registered User
 Join Date: Mar 2011
Location: Co
Posts: 412
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Re: Transmission ID?
The first is an SM420. SM465's have two PTO ports, SM420's have one.
I don't know what the second is.
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63 k20 with cummins 4bt, owned sence 1982 |
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03-13-2016, 07:49 PM
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#6 |
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Registered User
Join Date: Jun 2013
Location: joshua tree ca.
Posts: 1,484
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Re: Transmission ID?
X2 dieseldude ... looks like the 420 had the add-on back-up light kit ( found it )second one is a New Process 435....limited distribution in GM & Chevrolet trucks from 1968-1972
Last edited by jtrichard; 03-13-2016 at 08:02 PM. Reason: found second one |
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03-14-2016, 06:27 PM
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#7 |
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Registered User
Join Date: Aug 2010
Location: Southern CA
Posts: 1,605
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Re: Transmission ID?
Neither one looks like the other SM420's that I have, with the telltale bulge on the right side. Unless the design changed over the years? I have probably half a dozen 420's and none have that ribbing.
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03-14-2016, 06:29 PM
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#8 |
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Registered User
Join Date: Mar 2011
Location: Co
Posts: 412
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Re: Transmission ID?
Late model 420's IE '67 have the ribs.
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63 k20 with cummins 4bt, owned sence 1982 |
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03-14-2016, 08:39 PM
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#9 |
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Registered User
Join Date: Jun 2013
Location: joshua tree ca.
Posts: 1,484
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Re: Transmission ID?
This will help
The SM-420 4-speed transmission was produced by General Motors between the years of 1947 & 1967. It was the standard transmission for GMC 2500, 3000, 3500 & 4000 series Trucks, & an option for 1000 & 1500 series trucks. There was no option for any other transmission in GMC 2500 & 3000 Series Trucks. Starting in 1966 General Motors offered the NP-435GA for its light truck applications as an option. The NP-435-GA became the standard 4-speed some time in the late 1960s. The cast iron case with large bulge on the passenger side makes the SM-420 easy to identify. Ribbing was added to the bulge on later cases, my 1965 GMC 2500 has this feature. The ribbed SM-420 case should not be confused with the later SM-465 transmission. How can you tell which 4-speed your 1966 has, if reverse is to the driver & down, it's the SM-420, if to the passenger & down, it's the NP-435-GA. The SM-465 Replced the SM-420 in GMC truck in 1967. The General Motors Transmissions are also called Muncie by many folks. SM = Synchro-Mesh, NP = New Process. http://6066gmcguy.com/SM420.html Last edited by jtrichard; 03-14-2016 at 08:45 PM. |
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