Gather 'round, kids, for another tale from your local kit historian. Well, I try to be one, anyway. I must confess, I don't have as much experience with these kits as I do with my previous kit history installments so I know for sure I'm missing some details or have some information wrong. For that, I hope that the vast knowledge base we have here can help fill in the blanks.
To date, there have been four separate, but related, toolings of this style of truck (for those of you who didn't know already, Action Line is 67-72). It seems AMT and MPC shared the tooling for the Chevrolet pickups, using the chassis plate from AMT's Ford and Chevrolet annuals from 61-63. AMT also tooled a GMC pickup as well as a completely new Blazer/Jimmy set when those trucks came on the market for 1969. Near as I can figure, AMT and MPC were competitors at the time, but auto manufacturers tended to alternate suppliers for promos every year. Perhaps AMT and MPC struck a deal to share the tooling or, after AMT developed the tooling for the 1967 pickup GM demanded it as they paid for it and loaned it to whomever was supplying the promos that year (total conjecture; someone please clear this up!).
First kit on the market was the AMT 1967 Chevrolet pickup annual. As with previous annuals, the truck was a long box, with the option to build a stock truck, custom truck, and a tow truck.
For 1968, MPC released the same tooling however the same modifications to the full size trucks were made to the model. This was released under the product code MPC868.
By 1969, it seems as though both AMT and MPC were releasing kits. The basic truck body was updated to the new-for-69 grille. The MPC version was changed to a fire truck and the AMT version was a stock pickup with the camper shell previously seen on the 61-63 annuals.
Once again, in 1970 both AMT and MPC released versions of the tooling. AMT started with a desert theme that it would continue to use for the next few years while MPC had racing theme.