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Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
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| | | | Joined: Aug 2012 Posts: 2 Moderated | | Moderated Joined: Aug 2012 Posts: 2 | I have a GMC 550 with the following VIN on the data plate: W553XI024
It’s a tandem axle, 5 window truck. Has the Olds V8.
What else can be told from this number?
Does “024” mean it was the 24th 553 truck built? In just 57 or 54-57?
What does the “XI” mean? The “W”?
I know 553 indicates wheelbase.
Any help is appreciated. | | | | | Joined: Sep 2001 Posts: 29,269 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,269 | If this is a 550 series GMC, I strongly suggest that post this question on oldGMCtrucks.com. There are members who know alot about big GMCs. Spanky reads posts here & there - he knows big GMCs. | | | | | Joined: Nov 2005 Posts: 6,100 'Bolter | | 'Bolter Joined: Nov 2005 Posts: 6,100 | Hy mikedean58, welcome, your serial number breaks down as, W = six wheeler, 553 = 158" wheelbase, X = 1956 production I believe the balance of the number is regular production number which probably started at 1001. Your truck left the factory with a 324 cu. in. Oldsmobile V8 the standard equipment was an 11" dual disc clutch, an FO90 front axle, rear axles Eaton SS(A) 34M, transmission 5 speed 541GDS3. possible auxiliary transmissions 6231A or 6231B and air brakes, hope that helps | | | | | Joined: Nov 2000 Posts: 1,399 Camp Commandant | | Camp Commandant Joined: Nov 2000 Posts: 1,399 | Mike, post a picture when can. Some of us love big GMCs here too!
Last edited by Bill Marlow; 10/31/2019 5:22 PM.
| | | | | Joined: Jun 2011 Posts: 5,096 Crusing in the Passing Lane | | Crusing in the Passing Lane Joined: Jun 2011 Posts: 5,096 | GMC posts the engine displacement as the first 3 numbers of the engine SN, 370xxxx.
That engine is a 370 or became a 370 in subsequent years.
Ed
'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.
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