[bob prichard]

Hi, I was wondering if anyone here had ever found a factory installed motor from the early 70s without a partial VIN stamped in the usual location? I am trying to help a friend determine if his motor is the born with unit. Thanks for your help.

[Gary H]

Only time I've seen that is with a SR (Service Replacement block). Are you looking in the correct location(s)? Most common area is along the side of the timing cover about halfway down between the top and bottom of it on the passenger side. Another location is toward the top of the timing cover farther toward the outside of the block

[bob prichard]

Originally Posted by Gary H

Only time I've seen that is with a SR (Service Replacement block). Are you looking in the correct location(s)? Most common area is along the side of the timing cover about halfway down between the top and bottom of it on the passenger side. Another location is toward the top of the timing cover farther toward the outside of the block

I should have mentioned it doesn’t have an SR # either. It does have casting and date numbers, the two letter engine code and EUN(?) number, just no VIN.

[Simple Man]

Originally Posted by bob prichard

I should have mentioned it doesn’t have an SR # either. It does have casting and date numbers, the two letter engine code and EUN(?) number, just no VIN.

I believe the EUN number is on PHS paperwork, if you have that.

[Joe's Garage]

First one was a 428/370hp in a 1969 Grand Prix that we bought from the original owner. It was rusted beyond belief and we parted it out. This was in about 1985 - before GPs became somewhat collectible.

Second was a couple years later and was a 1971 GTO 400 engine that came out of a rolled and burnt GTO that we found in a wrecking yard in Tooele Utah. We bought the engine and transmission, then resold the engine about a year later. I think we still have the T400 somewhere.

Third one was a 455 in a 1973 Bonneville that was owned by a friend here in Las Vega$. We helped him change out the timing chain shortly after he bought it from somewhere back east. He drove it around for about three or four years and then sold it to someone out in California.

All of these had EUNS and correct matching date codes and engine codes. Just no partial VIN anywhere at all on the front surface.

Maybe we were just lucky enough to go through enough Pontiacs to stumble across these. I've gotta believe that there are/were more.

[Joe's Garage]

I think that they stopped putting the EUN on the billing sheets in 1968 or 1969.

Originally Posted by Simple Man

I believe the EUN number is on PHS paperwork, if you have that.

[65madgoat]

Quite possible this car's engine has one of them -- no VIN on it -- but dang oh so period correct and all. Not like 455HO blocks grow on trees. Never say never is what I say


https://bringatrailer.com/listing/19...ird-formula-2/

[Held for Ransom]

If the car was built at the California Fremont Plant (Z in the VIN) the partial stamp may be high on the engine block.
https://forums.maxperformanceinc.com...d.php?t=736578

[thepontiacman]

Some blocks may have partial vin over below passenger head on front of block .

Recently bought 69 GTO WT 400 with vin stamped there . Atlanta plant car .

Some later Trans Ams were stamped there also.

Sent from my moto g power 5G - 2023 using Tapatalk

[gtohurstjudge]

Some engines did not get stamped with a VIN......I've run into that a couple of times.

[poncho-mike]

There is an older thread that is much longer that goes into this. I had a 1971 YE 455HO with EUN, but there was no VIN stamped into the block. It had been vatted and was totally clean, not even a trace where one was stamped. I believe the explanation that someone gave was that if the engine failed during run-in, it was pulled off to the side and a different engine was installed off the manufacturing line. That line typically didn't stamp the VIN.

I have seen a total of three engines without VINs that I'm aware of. One was the 1971 YE 455HO, another was a 1970 YZ Ram III, and the third was a 1970 Grand Prix 455 XF code. There may have been more because I rarely looked at VINs on the block.

I want to say that on the YZ block, I became curious because the engine was much later than the cowl tag. When I went looking for the VIN, I couldn't find it.

[Tellyshavilli]

Originally Posted by Joe's Garage

I think that they stopped putting the EUN on the billing sheets in 1968 or 1969.

Yes stopped after 68

[Baron Von Zeppelin]

Originally Posted by bob prichard

Hi, I was wondering if anyone here had ever found a factory installed motor from the early 70s without a partial VIN stamped in the usual location? I am trying to help a friend determine if his motor is the born with unit. Thanks for your help.

If you can disclose more exact data
- the block casting date and the block code and the EUN stamped above the 2 digit code
- the last 7 digits of car VIN , and Body Date from Trim Tag
I can check those parameters against the data base and let you know if it is possibly original to the car.


If its a 73 Catalina , its just an anomaly .
If its a GTO or Trans Am - it will come under deep scrutiny

[Tellyshavilli]

Originally Posted by bob prichard

Hi, I was wondering if anyone here had ever found a factory installed motor from the early 70s without a partial VIN stamped in the usual location? I am trying to help a friend determine if his motor is the born with unit. Thanks for your help.

Yes, I’ve seen it more than a few times late 60s and early 70s not common, but it did happen

[bob prichard]

Originally Posted by poncho-mike

There is an older thread that is much longer that goes into this. I had a 1971 YE 455HO with EUN, but there was no VIN stamped into the block. It had been vatted and was totally clean, not even a trace where one was stamped. I believe the explanation that someone gave was that if the engine failed during run-in, it was pulled off to the side and a different engine was installed off the manufacturing line. That line typically didn't stamp the VIN.

I have seen a total of three engines without VINs that I'm aware of. One was the 1971 YE 455HO, another was a 1970 YZ Ram III, and the third was a 1970 Grand Prix 455 XF code. There may have been more because I rarely looked at VINs on the block.

I want to say that on the YZ block, I became curious because the engine was much later than the cowl tag. When I went looking for the VIN, I couldn't find it.

I remember reading somewhere that the 455HO motors were “hand fitted” at the factory. I can imagine other high performance engines having the same treatment, but I am only speculating. So, maybe its possible that during the extra attention the stamping was overlooked. Also, I have a friend who worked in the Fremont, Ca. factory, his father before him, who tells stories of things that didn’t go the way they were supposed to, to put it mildly.

[Baron Von Zeppelin]

All Pontiac engines were cast , machined , stamped , assembled , test run momentarily on a propane fixture - at PMD in Michigan.

Then shipped by rail cars to the various plants.
The various plants stamped only the VIN's on the engines.

[71GP76TA]

I recently sold a Van Nuys built '70 Trans Am that did not have a vin on the block. Engine appeared original to the car. All dates.. etc lined up with everything else. I applied muriatic acid to the area and nothing surfaced.

[Maxthe222]

Originally Posted by Baron Von Zeppelin

If its a 73 Catalina , its just an anomaly .
If its a GTO or Trans Am - it will come under deep scrutiny

I am very suspicious of them, as i've seen plenty with very faded stamps, multiple attempted stamps (pic attached), machined faces that hindered the stamp, but I really haven't come across a block that has no stamp at all on 70's Firebirds.

A friend was sold a "bandit" '77 4-speed T/A and was told it had a numbers matching block. There was no stamp at all on the face by the water pump, but there was the EUN. The date and cast codes showed it was impossible to be numbers matching, as it was the 418988* cast block, not a 500577. Upon further investigation, it was determined the face of that block had been machined down in the past for a rebuild, and the motor had been replaced decades ago.

[Bermuda Blue]

Originally Posted by Joe's Garage

I think that they stopped putting the EUN on the billing sheets in 1968 or 1969.

Canadian "PHS" (Vintage Vehicle Services )documents show EUN after 68.

[unruhjonny]

I am not sure how to reply, but I have had four different VVS packets;
None had the EUN listed.
Maybe you have some inside knowledge which might permit me to confirm this?