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| | | | Joined: Dec 2015 Posts: 3 New Guy | | New Guy Joined: Dec 2015 Posts: 3 | Have a 1954 Chevy 3100 and the tranny and differential are not the same ones as in the shop manual. Here are numbers off of them. TRANNY- GM 3845122 3707105 Q658 C1156 Differential- GM53 3896839 If you need photos send to my email Thanks for any info. Happy New Year jw4050@aol.com | | | | | Joined: Jun 2011 Posts: 5,096 Crusing in the Passing Lane | | Crusing in the Passing Lane Joined: Jun 2011 Posts: 5,096 | Tranny should be SM-420, could have been replaced by SM-465, which are both 4speeds, which started in 1968. Could also be a Saginaw 4 speed if side shift? Could also be an NP-540 if 4 shift rails and Al top cover, or NP-435 if 3 shift rails and Al top cover. Rear could be a Dana 44 or even a D-60, depending on 6 or 8 lugs, no telling what was swapped out, especially if it was originally a torque tube rear-others will have info on that. Do they work OK, or do they need help?
Ed
Last edited by EdPruss; 01/02/2016 5:50 PM.
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.
| | | | | Joined: Sep 2001 Posts: 29,270 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,270 | fire truck red, Do you have an open drive shaft, or do you have an enclosed drive shaft (the original configuration)? Can you see a universal joint? Can you post a link to a picture of your transmission? Is it a 3-speed (on the column) or a 4-speed (in the floor) transmission? If it is an SM420 transmission, and, if 3845122 is the the casting code, it might be a 1964-1967 SM420 four speed. If it is an SM420, the rear "cover" can be easily adapted to work with either an enclosed or an open drive shaft. | | | | | Joined: Mar 2006 Posts: 319 Shop Shark | | Shop Shark Joined: Mar 2006 Posts: 319 | Your tranny casting number (3845122) matches the tranny number from this post from 2014. Is This A Saginaw? So, I believe you have the SM 318 3 speed with a column shifter. Your number on your differential housing shows it is a 12 bolt. Here is a nice article from Hemmings on the 12 Bolt that may answer questions you haven't thought of yet. Hemmings 12 Bolt Info Hope this information helps.
"Nothing astonishes men so much as common sense and plain dealing." - Ralph Waldo Emerson
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