March VIN stamps are on the rough cast area on the bell housing flange of the block down by the starter. You will not likely find ANY clear pics of a VIN, unless it is a fake. They were not stamped very deep, and are normally NOT legible, except maybe two or three characters.
IMHO, they do not vary much from one month to another. Almost all are crappy. If you see one that is perfectly legible, there is a good chance, it is a fake. I have a few examples, but nothing from March that I am aware of. Pretty much all similar after Dec. 1968. All difficult, if not impossible to read.
Check this page out:
http://www.camaros.org/drivetrain.shtml#PartialVINs
"In the 1969 model year, the partial VIN for V8 engines was stamped in either of two locations: on the engine pad or near the oil filter. The alternator was moved to the passenger side in 1969 which covered the engine stamp pad and caused the VIN stamp to be relocated by the oil filter. The block in this area is raw unmachined casting which makes this stamp difficult to see. Generally, the Norwood plant stamped the VIN on the engine pad on early cars and moved the stamp by the oil filter in the December 68 time frame (there are a few known exceptions). Los Angeles was not as consistent and the VIN stamp location varied during the year."