[FirstOwner69]

"Numbers Matching" can be defined a couple different ways depending upon how much info GM actually stamped and cast on the blocks, heads, etc. That varies, even with Corvettes. According NCRS, until December 1959 or January 1960, Corvette engines had the same limited info cast and stamped as our trucks do. After that, Corvettes had a "VIN derivative" stamped in 5/32" digits added at the St. Louis Corvette assembly plant. Therefore, for the early Vettes, NCRS considers numbers matching to mean that the casting numbers, pad stamps and dates are reasonable for the presumed production date of the car. According to the NCRS 1958-1960 Corvette Judging Manual dated 1998 that would mean that:
"The engine block casting date must precede the engine identification stamping date; generally, by no more than 2 weeks. The engine assembly stamped date code will normally precede the theoretical vehicle assembly date 10 days to eight weeks..."

It makes sense to me that this same logic would apply to these trucks... until GM added the "VIN derivative" sometime after 1972.

Based on a discussion I had with Chevrolet in 1969, my 69 3/4 ton with a 350 was made the second week of December, 1968. Below are pictures of my block numbers and Protect-O-Plate which indicate that my engine is correct for a 3/4 ton truck, proper dates (cast November 27,1968, and assembled November 30) and original per the Protect-O-Plate. You will also note that whoever stamped the pad substituted an I for one of the 1s. The pad should have read "V1130XD" to reflect a November 30th assembly. A fairly common mistake.

Hope this helps.
Jim