bb or sb - The 1947 - Present Chevrolet & GMC Truck Message Board Network

caspear78 · 01-05-2004, 08:11 PM

ok heres one for the board, how can i tell what my truck had in it? some one has told me that the 70 gmc that i have came out with a big block but others say it came stock with small block. ,,,,,,,mark

TsgtE662 · 01-05-2004, 08:26 PM

My '70 GMC Sierra has the 396/402 BB. I'm pretty sure its the 402. And all the numbers appear to match up. Some GMCs had the SB and some the BB same as Chevys. The glove box decal should say what your truck came with if its still there.

caspear78 · 01-05-2004, 08:35 PM

the decal is there but it dont say, someone had told me that they could tell because it has leaf springs on the rear, then the same person had said it was a heavy halfton

TsgtE662 · 01-05-2004, 09:01 PM

From what I have read, GMCs had the rear leaf springs instead of the coils with trailing arms because at the time the general consensus was that leaf spring suspensions were heavy duty suspensions and alot stronger. My decal states it has a heavy duty rear leaf suspension and the camper special package too. So that wouldn't have much to do with the motor size really. Atleast thats the way I understand it. Also, on my heads with the casting numbers is a letter 'T' which I understand to mean 'Truck' as opposed to passenger type heads. And after running the numbers from another site, they were for a truck 402 engine. I have seen other GMCs with a 350 and still had the rear leafs. Can you read/make out the options codes or any info on your truck from that decal? Part of mine is faded/worn, but mostly readable. Mine also doesn't give the w/base numbers so I'm not sure on that.

caspear78 · 01-05-2004, 10:04 PM

ill have to go out and look at it but itll have to wait till after work tomorrow because its to cold out rite now to go fool with my truck,lol, im gonna start lookin for any and ever number i can find on there weather it be the frame or the block , i am startin to get more determined to find out, , if it is a big block set up im going to start lookin for everything to get it back to big block moter and tranny, but if it is a small block truck then so be it , ill get it back to stock if not better,lol

Longhorn Man · 01-05-2004, 10:23 PM

The springs don't make it a heavy half...that name wasn't even thought up untill 78 or so. The springs say nothing about engine size either.
If the sticker doesn't say any engine option, and it is a CE truck, then you had a 307 stock.

01-05-2004, 08:11 PM	#1
caspear78 Registered User Join Date: Oct 2003 Location: biwabik, minnesota, what is this white stuff out here Posts: 334	bb or sb ok heres one for the board, how can i tell what my truck had in it? some one has told me that the 70 gmc that i have came out with a big block but others say it came stock with small block. ,,,,,,,mark

01-05-2004, 08:26 PM	#2
TsgtE662 2A674 Tank Rat Join Date: Jul 2003 Location: Maryland Heights, Mo. Posts: 626	My '70 GMC Sierra has the 396/402 BB. I'm pretty sure its the 402. And all the numbers appear to match up. Some GMCs had the SB and some the BB same as Chevys. The glove box decal should say what your truck came with if its still there. __________________ '92 GMC Sierra, Sportside, 2wd, 350, Black '92 Chevy Silverado Extended Cab 4 x 4, Blue USAFR = 2A674 = Aircraft Fuel Systems Maintenance i.e. Tank Rat

01-05-2004, 09:01 PM	#4
TsgtE662 2A674 Tank Rat Join Date: Jul 2003 Location: Maryland Heights, Mo. Posts: 626	From what I have read, GMCs had the rear leaf springs instead of the coils with trailing arms because at the time the general consensus was that leaf spring suspensions were heavy duty suspensions and alot stronger. My decal states it has a heavy duty rear leaf suspension and the camper special package too. So that wouldn't have much to do with the motor size really. Atleast thats the way I understand it. Also, on my heads with the casting numbers is a letter 'T' which I understand to mean 'Truck' as opposed to passenger type heads. And after running the numbers from another site, they were for a truck 402 engine. I have seen other GMCs with a 350 and still had the rear leafs. Can you read/make out the options codes or any info on your truck from that decal? Part of mine is faded/worn, but mostly readable. Mine also doesn't give the w/base numbers so I'm not sure on that. __________________ '92 GMC Sierra, Sportside, 2wd, 350, Black '92 Chevy Silverado Extended Cab 4 x 4, Blue USAFR = 2A674 = Aircraft Fuel Systems Maintenance i.e. Tank Rat

01-05-2004, 08:35 PM	#3
caspear78 Registered User Join Date: Oct 2003 Location: biwabik, minnesota, what is this white stuff out here Posts: 334	the decal is there but it dont say, someone had told me that they could tell because it has leaf springs on the rear, then the same person had said it was a heavy halfton

01-05-2004, 10:04 PM	#5
caspear78 Registered User Join Date: Oct 2003 Location: biwabik, minnesota, what is this white stuff out here Posts: 334	ill have to go out and look at it but itll have to wait till after work tomorrow because its to cold out rite now to go fool with my truck,lol, im gonna start lookin for any and ever number i can find on there weather it be the frame or the block , i am startin to get more determined to find out, , if it is a big block set up im going to start lookin for everything to get it back to big block moter and tranny, but if it is a small block truck then so be it , ill get it back to stock if not better,lol

01-05-2004, 10:23 PM	#6
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	The springs don't make it a heavy half...that name wasn't even thought up untill 78 or so. The springs say nothing about engine size either. If the sticker doesn't say any engine option, and it is a CE truck, then you had a 307 stock.



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