Big Block Numbers - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Purs · 04-03-2003, 10:06 AM

I got these numbers off a Big Block and was wondering if someone could help me figure out what it's out of or what it is. These numbers are off the front pad on the passenger side head. Also, what is the second set of numbers for?

10524TRW
C4A176626

Call me stupid but I've already been to MORTEC and still can't figure it out.

Mike C · 04-03-2003, 10:48 AM

www.nastyz28.com has small block suffix codes but not big block. (The TRW code, but GM switched to 3 digits in 1970, so that says it is newer than 1969.) The first set of numbers is then engine number and suffix code, the second set should be the VIN from the original vehicle.

To use Mortec, you need casting numbers. On the block it will be on the bellhousing flange on the drivers side. For the cylinder heads it will be underneath the valve cover between the rockers.

Hutch · 04-03-2003, 01:59 PM

This is what I found:
On this page:

1974 TRW Truck 454 245 400 LS-4 VIN Z, L, f.d, 20, 30
1979 TRW Truck 454 210 400 LF-8 VIN S, fwd, 20

DSO Codes

Not sure if this is correct information
Does the vin match the second number?

Have fun

Purs · 04-03-2003, 03:06 PM

thanks guys for the info. What's the easiest way to tell between a 400 (402) and a 454?

Hutch · 04-03-2003, 04:01 PM

I am not sure but the number at the rear of the block would help and also a date code maybe even the numbers off of the heads under the valve covers. There is also a date code on the heads.

Mortec explains the location of the numbers:
Mortec Number locations

I am sure that someone on this board can tell you a quick visual way to tell what you have.

Have Fun

04-03-2003, 10:06 AM	#1
Purs Got Big Block? Join Date: Apr 2000 Location: West Texas Posts: 1,510	Big Block Numbers I got these numbers off a Big Block and was wondering if someone could help me figure out what it's out of or what it is. These numbers are off the front pad on the passenger side head. Also, what is the second set of numbers for? 10524TRW C4A176626 Call me stupid but I've already been to MORTEC and still can't figure it out. __________________ "Experience is what you get when you didn't get what you wanted." Last edited by Purs; 04-03-2003 at 11:04 AM.

04-03-2003, 10:48 AM	#2
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,714	www.nastyz28.com has small block suffix codes but not big block. (The TRW code, but GM switched to 3 digits in 1970, so that says it is newer than 1969.) The first set of numbers is then engine number and suffix code, the second set should be the VIN from the original vehicle. To use Mortec, you need casting numbers. On the block it will be on the bellhousing flange on the drivers side. For the cylinder heads it will be underneath the valve cover between the rockers. __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

04-03-2003, 01:59 PM	#3
Hutch Registered User Join Date: Oct 2001 Location: Grapevine, Tx. Posts: 2,140	This is what I found: On this page: 1974 TRW Truck 454 245 400 LS-4 VIN Z, L, f.d, 20, 30 1979 TRW Truck 454 210 400 LF-8 VIN S, fwd, 20 DSO Codes Not sure if this is correct information Does the vin match the second number? Have fun __________________ John Hutchison Grapevine,Texas 68 1/2 t swb 68 Mustang 69 Jaguar 71 1/2 t swb 88 Supra CompTs6m 93 Escort GT 2005 Corolla XRS

04-03-2003, 03:06 PM	#4
Purs Got Big Block? Join Date: Apr 2000 Location: West Texas Posts: 1,510	thanks guys for the info. What's the easiest way to tell between a 400 (402) and a 454? __________________ "Experience is what you get when you didn't get what you wanted."

04-03-2003, 04:01 PM	#5
Hutch Registered User Join Date: Oct 2001 Location: Grapevine, Tx. Posts: 2,140	I am not sure but the number at the rear of the block would help and also a date code maybe even the numbers off of the heads under the valve covers. There is also a date code on the heads. Mortec explains the location of the numbers: Mortec Number locations I am sure that someone on this board can tell you a quick visual way to tell what you have. Have Fun __________________ John Hutchison Grapevine,Texas 68 1/2 t swb 68 Mustang 69 Jaguar 71 1/2 t swb 88 Supra CompTs6m 93 Escort GT 2005 Corolla XRS



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