Realize this is a very old thread but it's also very wrong.
* The DL is probably BL for Los Angeles (Van Nuys); 1970 Chevelles were not built in Doraville, GA.
* 791779 is not an accessory code but rather a data processing number used for internal tracking - of no real significance today unless you find a build sheet and this number corresponds to the first 6 numbers in block 24.
* 220311 is a concatenation of two different numbers from the build sheet; 03 is the SCHED NO. found in block 10 and on Van Nuys sheets this indicates the work day of the month - the 3rd day in this case; 0311 is, again, a data processing number found in block 24.
* The explanation about even/odd trim tag style numbers comes from Alan Colvan's book and it is wrong. Depending on the year and the assembly plant, some plants DID code a 6-cyl engine on the trim tag. I have a matrix of 1964-1972 Chevelles and all the production plants showing one of 4 things; (1) whether a plant in that year is known to have coded odd digit style numbers (such as 13380), (2) whether a plant in that year is not to have NOT coded odd digit style number (but the VIN may still show an L6 car), (3) plants and years where no even third digit style numbers have been found yet (all examples so far are even 3rd digits and all happen to be V8s as well), and (4) plants that did not produce Chevelles for a given year.
The sequence number starts with 1000000?..28,822 Chevelle car built?...first week of January?...Man they built a lot of cars...although the sequence number probably started in 1973? Interesting.
No. First the number(s) on the trim tag is NOT a GM VIN sequence number. Second you have too many digits, sequence numbers are 6 digits long and for 1974 Chevelles/El Caminos/Monte Carlos in the U.S. begin with 400,001. You'd have to check your VIN tag (not the Fisher Body number plate) for the buid sequence number. If the last 6 digits of your VIN are, say, 410,125 then your El Camino is the 10,125th 1974 Chevelle (all models) built at Fremont that year.