Earliest 1970 Block ??
 

There is an ad on e pay showing a block calling it a late 69

But the WT block is stamped 70

The question is the block shows F 19 9 June 19th 1969

This is one of the earliest block I've seen for 1970 gto

9799914 to me definitely a 70 block

Here is the ad cant figure how to upload
1969 Pontiac GTO 400 4 spd WT Engine Block 48 Heads 1111970 Distributor 69

I will try to find it and give it a once over.
The EUN - if high number - means it's a late1969 model.
EUN - if low - means it's an early 1970 model.
A legible stamped VIN would identify it also.
Motor mount bracket bosses another indicator.

They started using that casting around May of 69 , with 70 cast in raised numbers by distributor.

It is a late 69 WT block with somewhat close dated #48 heads - E229
The high EUN 0819915 determines it for sure.
It was the 819,915th engine produced for 1969 model year.

70 model use that early would have a very very low EUN

https://i.ebayimg.com/images/g/ZM0AA...Wv/s-l960.webp

There's a 9799914 block on the Wallace EUN search page that was cast in March of '69

Sequential , but usually in batches of engine family.
The EUN was multi-dimensional.
One of its uses was quality control concerning potential defective parts.
Technical bulletins issued would reference potential problems by EUN range.
A potential lesser batch of bearings, potential lesser batch of timing gears, etc...

1968 was highest production year
1973 was second
I think 1969 was in the top 5
They never hit 1,000,000 in a year

Some of the EUN entries on Wallace site are provided by random contributors.
Always some entries that seem erroneous or questionable , he lists them all for end user discretion.
Some are obvious , and some are just head scratchers.