hello, i might have discovered very bad news. I need your help in trying to figure this out. I'm not sure if my 74 actually came with the 454 that's in it. The engine and tranny do match the vin, but i'm not sure that it's the right vin. Are there different differentials for a 350 and a 454? Here's the numbers, any help would be greatly appreciated. The diff: 3871375, the vin: 1Z37Z4S409524, tranny: 3999289, engine: 14S409524 & T1108CWM. The car is black now, was supposed to be silver. This could really affect what happens with this car. It would be great if you guys could tell me what you know and think. Thanks

Several gears could have been ordered depending on weather it was a manual or auto trans and if the person placing the order asked for the one put in it. Manuals usually got a 3.36. Auto trans with L48 engine usually got a 3.08. An auto trans with L82 engine usually got a 3.55. However you could have ordered others as well.

You say: "......I'm not sure it's the right VIN". What do you mean by this? Do you mean the VIN on the windshield post may be wrong or ???

Assuming that the VIN is correct, it's quite simple... the 5th digit determines the motor, in your case "Z" for the 454.I doubt that the VIN tag has been changed because it ( the number) wouldn't match the ownership (or pink slip).BTW other designations for that year were
"J"-base or L48
"T"- L82

ok, i think that someone may have switched the vin plate, meaning that it would be possible to have the right engine for the current vin. I am worried it is entirely wrong, isn't there a possibilty the vin changed on the title?, or he used the title that he took the vin number from?? I was wondering if the rear end is different for a 350 than for a 454, i've heard on here that the u joints have different bolts, this would be a good indicator of whether or not it is the original engine/tranny. thanks

the vin plate is spot welded on the windshield pillar
and it should be noticeable if it has been changed, you may have to remove the trim to be sure. as for the rear end it could of been blown up any time and replaced with one from a small block. the shaft bolt caps will be a thin metal strap if it is from a small block, a big block will have a big metal cap. also look to see if it has a rear sway bar, or a sign that one was bolted to the frame. you can remove the drivers rear wheel and clean the top of the frame to find the stamped vin in that location. i herd you can see it with a small miror
and get a rubbing of it to compare to the pillar vin
jay

I believe the chassis should be stamped with the VIN somewhere- not sure offhand. I would check into that for sure.

Hello all,

There were several place the VIN is found. The pillar post, the drivers door on the end near the latch (blue laminated paper), and on the top of the frame drivers side forward of the trailing arm bend. With some work, you can use a small metal scrub brush to fit between frame and body to clean the numbers and use a mirror to see them.

Also look at the rivets on the VIN tag on the pillar post. If they are like a standard aluminum pop rivet then the tag has been re-riveted. The rivets should have a "Daisy flower" look to it. (Hard to describe, but once you have seen one you will understand what I am describing.)

Earlier BB cars had caps as opposed to U bolts on the half shaft universal joints. However, I am not sure this was the case for the later BB cars.

I would not be too concerned unless you get proof that the frame is different than the block and pillar.

Because the 74 BB does not fetch the huge prices of the earlier BB cars (65-72) it doesn't really make a lot of sense to try to fake a 74 BB. But you never know.

Alex

thanks for all the input, here's the situation, there are two welds on the driver's side pillar, and one on the passenger side. I looked at another corvette and there was one weld on each pillar. i don't know what's going on. It would make sense that the 74 didn't have the cap bolts for the rear because they simply did not have the horsepower. But however, mine now has that much horsepower and i'm worried i might blow a 350 diff. I'm going to check the numbers on the frame and hope for the best. The weird part is, i talked to the owner from 1980, she said it had a 454, and that it had been sitting for several years when she bought it. It makes it seem even more strange to try and transplant the 454. I'll let you know what i find. Thanks for now.

i can't seem to find the numbers on top of the frame when i take off the right rear wheel. Is it near the front of back when you take off the wheel?? any help would be great