OK folks let me start from the beginning. Kinda long, sorry. Previous owner told me a lady that lived 3 blocks from him bought my car new in 68, (originally a 302 car) drove it for a year took it back to Ford and told them she wanted more power. They put a 351 in it for her and she drove it till the mid 80’s when the guy (who had lusted over the car since 68) had the chance to buy it and did. He said to the best of his knowledge it had never been touched other than a water pump and fuel pump. I looked up the casting number off the block, sure enough a 69. I get my block back from the machine shop last night and notice 8 (9R190563) numbers stamped in the back where the bell housing bolts to the engine. I’ve been trying to research these numbers and can’t really come up with a decent answer. Some guys claim Ford did not stamp anything till well into the 70’s while others claim they only stamped the “special” and/or “high performance” engines in the late 60’s early 70’s to match vin numbers. So I guess what I am asking is what do they mean??? Thanks!
Sounds like a VIN stamp to me. They were legally obligated to stamp the VIN on all engines & transmissions starting in 1968 (iirc).
Starting on January 1st 1968 all vehicles were required to have the VIN stamped on the engine and transmission. This was a part of the Federal Motor Vehicle Safety Standard. The FMVSS covered a variety of things from the installation of shoulder belts for front seat occupants to standardizing the PRNDL shift pattern for automatic transmissions.
The number you are seeing is a typical partial VIN that would have been stamped on both the engine and transmission on any vehicle built after 1/1/1968. 9 is for 1969 the R is for the San Jose plant the 1 means it was installed in a Ford not a Mercury (5) And the sequential build number.
Thanks guys! Assuming this guys story is correct if this engine was installed in 69 and it is a 69 should I assume Ford pulled it from a wrecked car? Why would it have a partial vin number? Or is there something I’m missing here?
The complete VIN is not needed to identify the car it came out of… All the important stuff is there for that purpose.
Yup, partial VIN is normal. Some cars were more partial than others too, depending on who was stamping that day 
Being the cynic that I am, I’d guess what’s missing is the true story. I have a hard time believing some woman would take a brand-new car back to the dealer and have them swap out engines…and what they stick in is a “new” (at that time) 351W–with the VIN from a Mustang? And I also can’t imagine why a dealer would get a wrecking yard engine–or why would a dealer have a wrecked Mustang sitting around? Dealers today don’t seem to have wrecked cars on the back lot? More likely, after she drove the car for years and didn’t keep up on the oil changes, and it started to burn oil and run poorly. So she took it to her local mechanic and for whatever reason at the time, it ended up with the 351W.
X 2
OR… She took it to the dealer wanting more power. The dealer wanted to make her happy and make some money. He happens to have a 351 car on the lot. He pulls the brand new 351 out of that car and installs it into the '68. He then orders a replacement 351 from Ford, claiming it was DOA and it gets paid for by Ford. He sells the old 302 out of the back door and laughs all the way to the bank.
OK, I think I like Mike’s story the best!! 
I have another story: this woman looked pretty good at the time and was married to a strong man who was heavy… on the gaz pedal I mean… and burnt the engine in his endless enthusiasm! Then he found this 351 Mustang on the stolen market and the woman never new about it since she never cared about mechanical stuff anyway!!! And that is, assuming, there actually was a woman involved in the story at all 
… OK guys, have a good night!
That’s a winner right there! LOL!
Getting pretty deep in here! 
My data shows Torinos and Fairlanes were also built at the San Jose assembly plant in 1969, and they a shared the Consecutive Unit Number series with Mustangs. So this engine is not necessarily from a Mustang.