What if the F8U-3 had won

[kerick]

The AF would've bought lots more F-105s, and the proposed RF-105 would have gone ahead. Then there's the export market for the Thud....
Air-to-air in NVN is a good question. I would expect MacNamara and his Whiz Kids to tell the AF to buy the F-8, whether or not the AF wanted it or not.
I'm still glad McAir won out, though.  

Maybe the USAF would have figured out the Falcon missile was crap a lot sooner. Could Sidewinders be retro fitted onto an F-106?

[Snowtrooper]

Could Sidewinders be retro fitted onto an F-106?

At the cost of halving the missile capacity, yes (or introducing external pylons). Sidewinder is much longer than Falcon, and the internal bays were designed around two Falcons in tandem.

Of course the Falcon could also have been further improved even from the D model as the Swedes did with their locally built Rb 28 variant, which featured a further improved seeker and most importantly, a proximity fuse.

[KJ_Lesnick]

kerick

Maybe the USAF would have figured out the Falcon missile was crap a lot sooner. Could Sidewinders be retro fitted onto an F-106?

They're too long; it is possible to carry a pair under the wings.  Other possibilities could include

• 3 x AIM-7 Sparrow
  
• 3-6 AIM-26 Falcon
  

The F-102 could carry either 2 x AIM-26 or 1 x AIM-26 and AIM-4 in the center bay; theoretically this would be doable on the F-106 if it was wired to fire them.  Some F-102's were later wired to carry AIM-26's in the outer bays, though I don't know if it was the following

• 1 x AIM-26 in each outer bay
  
• 1 x AIM-26 + 1 x AIM-4 each outer bay
  
• 2 x AIM-26 each bay
  

The F-106's didn't have a divided bay but the capcacity should work