I'm not sure if the production rate is dynamic in v1.3. It never used to be. However, the DC8 production line in JA5 is messed up because it has some kind of bug (this has been reported). When I initially ordered my -31s they were set to be delivered within a couple of years. However, once I started ordering other versions, -53s etc, those were inserted into the schedule ahead of the -31/33s and my initial orders were pushed back several years. There are now 6 month gaps between batches in my orders that shouldn't be there, and half my -31s will now be delivered after I get all my -53s. Not how it is supposed to work at all. You might want to check your own schedule to see it you have the same issue.