Decode transmission numbers - The 1947 - Present Chevrolet & GMC Truck Message Board Network

72c20customcamper · 08-12-2025, 01:45 PM

I have the transmission out of my 68 I cleaned up the tag but the paint is gone for the most part but looks like 68t-549. And at the bottom CT68 -77660 . I’m guessing it’s a 68 trans but not sure if it’s original to the truck

**mr48chev** · 08-12-2025, 03:09 PM

I checked the GM heritage center vehicle info kit and all it says is powerglide or turbo400 https://www.gm.com/content/dam/compa...olet-Truck.pdf

Over on Chevy hardcore I found info that should be useful to you https://www.chevyhardcore.com/tech-s...and-turbo-400/ Scroll down the page and you will find his piece. that reasonably tells you how to decode it and that there should be another number stamped on the case. 68 was right at the start of "matching numbers" that were actual matching numbers in that partial serial numbers of the engne and trans matched the vin rather than just telling that the engine or trans was built for a 65 C10 with a 283 or a 53 3100 with a 235.

72c20customcamper · 08-12-2025, 04:09 PM

Definitely a 400 the pan shape and 13 bolts with the vacuum modulator on the passenger side . Also has electric kick down there are no numbers on the area in the picture . I don’t believe GM did any partial vin stamps on truck components.

Pan looks like this

08-12-2025, 01:45 PM	#1
72c20customcamper Registered User Join Date: Jul 2018 Location: Catskill Mountains,NY Posts: 9,482	Decode transmission numbers I have the transmission out of my 68 I cleaned up the tag but the paint is gone for the most part but looks like 68t-549. And at the bottom CT68 -77660 . I’m guessing it’s a 68 trans but not sure if it’s original to the truck Attached Images __________________ Mark 72 c20 custom camper Husky edition, 66 SS396 Chevelle 1964 Hawk, 63 Avanti,62 lark 1969 AMX , 1968 c20 stepside ,85 K20 1977 Suburban sold 68 anniversary.

08-12-2025, 03:09 PM	#2
mr48chev Registered User Join Date: Jul 2007 Location: Toppenish, WA Posts: 16,400	Re: Decode transmission numbers I checked the GM heritage center vehicle info kit and all it says is powerglide or turbo400 https://www.gm.com/content/dam/compa...olet-Truck.pdf Over on Chevy hardcore I found info that should be useful to you https://www.chevyhardcore.com/tech-s...and-turbo-400/ Scroll down the page and you will find his piece. that reasonably tells you how to decode it and that there should be another number stamped on the case. 68 was right at the start of "matching numbers" that were actual matching numbers in that partial serial numbers of the engne and trans matched the vin rather than just telling that the engine or trans was built for a 65 C10 with a 283 or a 53 3100 with a 235. Attached Images __________________ Founding member of the too many projects, too little time and money club. My ongoing truck projects: 48 Chev 3100 that will run a 292 Six. 71 GMC 2500 that is getting a Cad 500 transplant. 77 C 30 dualie, 454, 4 speed with a 10 foot flatbed and hoist. It does the heavy work and hauls the projects around.

08-12-2025, 04:09 PM	#3
72c20customcamper Registered User Join Date: Jul 2018 Location: Catskill Mountains,NY Posts: 9,482	Re: Decode transmission numbers Definitely a 400 the pan shape and 13 bolts with the vacuum modulator on the passenger side . Also has electric kick down there are no numbers on the area in the picture . I don’t believe GM did any partial vin stamps on truck components. Pan looks like this Attached Images __________________ Mark 72 c20 custom camper Husky edition, 66 SS396 Chevelle 1964 Hawk, 63 Avanti,62 lark 1969 AMX , 1968 c20 stepside ,85 K20 1977 Suburban sold 68 anniversary. Last edited by 72c20customcamper; 08-12-2025 at 04:30 PM.



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