Big Block on VIN plate - can you tell?
 

Do the GVW numbers decipher whether a SWB truck had a big block or not?

JQ

Re: Big Block on VIN plate - can you tell?
 

In 1972, All domestic 1/2 ton Big Block trucks were required to have both heavy front and rear springs. This requirement enables us to determine if the truck was originally equipped with heavy front and rear springs by viewing the weights on the Gross Weight/VIN plate. If the truck was originally equipped with heavy front and rear springs, The "As-Manufactured" (left-hand figures) Gross Weight for this Vehicle Must be 5400 pounds, the Maximum Front End Ground Weight must be 3100 and The Maximum Rear End Weight at Ground must be either 3220 or 3500. Remember, not all trucks with these Gross Vehicle Weights were Big-Blocks, but all Big-Blocks have these Gross Weights. AGAIN, THIS IS ONLY FOR 1972 1/2 Ton Trucks!!! See examples.

I also look for original rivets on the VIN plate, frame # matching, exhaust brackets, etc.

Re: Big Block on VIN plate - can you tell?
 

Nice Tip Dan. Trevor

Re: Big Block on VIN plate - can you tell?
 

So in 1972 at least, the vin will tell you if was a BB, but the vin will not tell you if it was a SWB?+

I SEE IT WONT TELL YOU IF IT WAS A BB, RATHER IF IT DOES NOT HAVE THOSE WEIGHTS IT WAS NOT A BB.

Re: Big Block on VIN plate - can you tell?
 

Some good info here!

Re: Big Block on VIN plate - can you tell?
 

The SPID will have the VIN #, wheel base and the model # info. As mentioned previously by Dan, you look at all these areas to authenticate the truck.

Re: Big Block on VIN plate - can you tell?
 

Here is the order I look at when determining the originality of an alleged '72 SWB BB truck.

1) VIN plate/Correct Gross Weights/Original Rivets?
2) Original SPID/Matches VIN Plate?
3) Frame Partial VIN match?
4) Frame Rail Part Numbers Correct for SWB?
5) Correctly Located/attached dual-exhaust brackets?

If any of these are not correct, I personally wouldn't be interested. Many other people don't sweat the originality details, but I will definitely pay significantly more for a correct/original SWB BB truck.

The other unique Big-Block items can be found and installed to look 100% correct and original. I feel pretty confident I could not be fooled by "put-together" truck.

Re: Big Block on VIN plate - can you tell?
 

Did all big block trucks have dual exhaust?

Re: Big Block on VIN plate - can you tell?
 

Every "factory" big block truck I parted out or owned had dual exhaust hangers.

Re: Big Block on VIN plate - can you tell?
 

I too have never seen a factory big block truck or car with single exhaust.

Re: Big Block on VIN plate - can you tell?
 

anyone know if the weight ratings in 1971 big block trucks were different?

Re: Big Block on VIN plate - can you tell?
 

The 72 1/2 ton Big-block trucks were required to have heavy front and rear springs. The 71 and earlier were not.

Dan

Re: Big Block on VIN plate - can you tell?
 

ahhhh. ok thx for reply! dave