ORIGINAL: ComradeP
So the eventual number of conversions/production of the new type does depend on having the older type in the pool? In other words: if you somehow have no or a very limited number of Panzer IVG's in the pool, less Panzer IVH's will be produced than when you have a higher amount of Panzer IVG's in the pool?
No, out of production equipment in the pool is only there to be available to be re-cycled back into combat if casualties become excessive. If not needed, the old equipment will eventually disappear from the pool. You can think of that as a conversion but there is no 1 for 1 relationship between what's eliminated from the pool and new production.
To put it another way, if the Germans historically produced 15,000 Panzer IVhs (just an example, I can't recall the actual number off the top of my head) and 1,000 of these Panzer IVhs were converted Panzer IVgs the production system will produce 15,000 Panzer IVhs and ignore the conversions since in game terms there would be no way to know what the actual number of Panzer IVgs available for conversion would be.