Question: Is the #VMA-M340U P51D Mustang retract ready? Have there been different configurations and different fixed gear sets supplied in the kit?
Answer: Yes to both questions.
Better Answer: Yes the VMAR #VMA-M340U Mustang is retract ready. All except the earliest models made prior to mid 2003.
There have been a number of variations of the factory implementation of the retract cavities.
Mustangs made from mid 2003 to the summer of 2004 had the cavities cut out at the factory and lined with plastic inserts and a set of flat covers were provided that modelers could attach with ZAP or Pacer Dap-A-Goo (works best) if retracts were not being installed.
Beginning summer 2004, the factory pre-installed the retract rails etc then they are covered over. Modelers who wish to install retracts can cut away the covering and install the plastic cavity inserts ONLY if they wish to install retracts. The plastic cavity inserts are included in the kit. We recommend Pacer Dap-A-Goo for installing the cavity inserts. Always test fit and test a small amount of any adhesive on any plastic and covering before proceeding.
When the VMAR Mustang 45-60 ARF was made retract ready, the fixed gear that comes with the kit were changed to allow the fixed gear to be bolted into a standard block mounting cavity that could later accomodate optional retracts. The instruction book may show wire fixed gear being fitted into slots in the wing. This is correct for models produced prior to mid 2003. Since mid 2003 the fixed gear uses a block mounting system with screws (4/wing) instead of the slots and clamps used in earlier production. | 
