Fastmark, no, they did not stamp later blocks like that, the pads were blank aside from possible machining notes and the WT (Water Tested Block) which all Hemi blocks were supposed to receive after being tested.

A couple pictures from a 1966 coronet 440 that is a hemi automatic car. The SPD of the car is 404 66. Block casting date appears to be
1-16-66. The assembly date looks like 3/2/66 or so.

a couple from another 66 engine I bought, 3-27-66 casting date, 4-19-66 assembly date.

That is a Mega block, not a OEM Mopar hemi cast block
the cast in M being the key
I look at that picture a little closer and maybe that is NOT a M
I have a Mega Hemi block motor in my shop now in a 1969 R.R. so I will look at it a little closer later, it definitely has the cast in M on the passenger side, I'll have to look at the casting number on that side of the block

What block are you referring to?
Matt

Cab here are the 2 mega block castings 1 has full water jackets the 1 with Mopar is siamese.

Mike

Mega block casting markets look nothing like a stock block. You can't confuse them when you look at the casting markings.

Dragonslayer, do you know when the machined pad was started on the Hemi engines?

Which machined pad on which block ?

I am not the expert on that, but believe 69 started the stamp on the pad of OEM production blocks.

There were some blocks cast in 1974, would have to dig some old Chrysler Performance Books up to remember if there were any long blocks with 1974 Casting or short blocks. I remember Mancini in around 1978 got a few short block Hemis and had them for sale but I dont remember the casting dates on the blocks. The stamping on the bottom of the pan rail I have never come across those markings on another block that was cast in 72-74.The Markings on that pan rail tell the story of the block,.when it was machined, when it was assembled and what number it was assembled at and what year is might of gone into. Since 1974 and up there were no Hemi Vehicles I know of being built the block would be an over the counter something. Top Fuel, Funny Car did not run this block at this time would of been a Keith Black likely for them.

I see this is an old thread. Another NOS D5 Block example with casting date 1-19-70. Casting number is 3577430.

I have an NOS 1974 casting PN 3690010 with the description in the 1973 catalog as 'Hemi Engine - Blown'.

Pics..?

Thought block in my last post was a blower block as well until I recently discovered it's a D5 block. Literally, there is NO information about D5 Blocks outside of what folks have posted. All Hemi blocks at that time were cast here in Indy, but this has a different casting number. As far as I can tell, it is a normal casting with the heavier webs and a relocated exhaust pushrod holes.

Be nice to hear from someone who may know more about the D5 Blocks...

Buried in the shop. I'll see if I can get to it, no promises. The only way I had of knowing the PN was that what was on the cardboard box it came it. Box has disappeared over the 30 years I've had the block but I recorded the PN as I recognized even then it was an odd PN.

Some guy awhil back posted that he worked at the foundry that made those blocks and there were many pallet full (a lot) sitting outside, mid 70s or so

wasn't letting the blocks sit outside supposed to "season" them ?
i remember hearing or reading about that in that time frame.

Did some digging today and found out some additional information. Talked to a gentleman in Illinois who was a close friend of Tom Hoover and worked in the racing industry during that time. Yes, there was such a thing as a D5 block for the D5 Heads. He had not seen a D5 block, but know they existed. He suggested talking to Ray Barton, he may know more about it.

Reached out to Ray and yes, they were a Pro Stock block for the experimental D5 head program and had less water jacket in the Intake pushrod area to allow for the relocated intake pushrod closer to the cylinder, thus the different casting number. He mentioned building a few blown drag boat engines using those blocks in the past and use to come across them from time to time. The block will accept regular Hemi heads without modifications, but was designed for D5 heads.

Now, just have to decide what makes sense for it...

Hi all. I’m the guy that worked at the Chrysler Indianapolis Foundry, hiring in the plant originally as a clerk in early 1972. There were a few hundred Hemi blocks (non-machined castings) in the storage yard at that time. One of my duties was to inventory the 100,000 +/- castings weekly.
I was drafted into the Army in October 1972 so not sure what occurred in ‘73-‘75 but Hemi blocks were gone when I came back. When plant was closing in mid 2000s a friend in Production Control asked if I was interested in some old files and gave me a copy of the plant Gross Production Record sheet issued in July 1997 (see attached). It lists castings (in 1000s) by year and block (Cu. In. Displacement) since 1961 so it covered Chrysler in-house Hemi block production. This would not cover later outsourced (other Foundries) production. When I returned to the plant from the service the Hemi tooling was also gone. Don’t know it’s status. Hopefully I got this Product Record to attach properly. Happy Veterans Day my brothers and sisters! Tom Kelly

Sorry upside down. Looked ok when I attached it. Hopefully someone smarter than me can correct it!😊