Good morning. Hoping you guys can offer me some guidance on the purchase of a vintage piece. I've been collecting watches for many years, (including a number of Breitlings) rotating my collection several times over, more recently starting to move towards those pieces which are considered timeless which have remained in production for many years. Still I've been purchasing new or like new models. However, recently the older Navitimers (1960's models) have caught my attention and I'm hoping you can offer some suggestions. In particular I like the 806 model with its reverse panda dial and at 41 mm a bit larger than most vintage watches that I've seen of this era. Anything in particular I should be looking for in terms of the model (809 vs. 806), are certain years more desirable, should I be looking at the AOPA models, are there ones which are considered more rare, collectible, or likely to maintain their value over time, are there some I should not consider for any reason, etc. I'm ballparking a purchase somewhere $5k or less which based on some early research would seem to put most of these models within reach but Ill defer to the experts here.....Thank you in advance.