Since we can’t use 550s and 775s from Banebots, has anyone seen a definitive ruling on the 775s from AndyMark (I may have missed an announcement)?
Assuming the AM 775s are still legal to use, would we be able to take a 775 motor off of the PG71 gearbox and use in a versaplanetary gearbox or would that be considered a modification? I see AM does sell 775s separately.
I can see where all AM 775s are spoken for before 1/9/2016. 
Yes. The motor is in FIRST Choice, and every year motors that have been in FIRST Choice have been legal.
Note that the AM 775s are MUCH less powerful the the Banebots were. It has about 1/3 of the stall torque, with about 1/3 of the free speed that the banebot had.
With the typical disclaimer that 2015 rules =/= 2016 rules…
The only motor I recall where you had to use the provide gearbox is the window motor (and maybe van door or snowblower, but I’m not positive about those). Swapping gearboxes is otherwise entirely fine.
Since the bare 775 (AM 9015) motor is available on firstchoice, one would assume that it is 2016 legal without the gearbox. :]
The 9015 is a RS500 sized motor: http://www.andymark.com/product-p/am-0912.htm
The Andymark 775 motor can be found with two different pinions and with/without a backshaft for an encoder.
http://www.andymark.com/RS775-p/am-2161.htm
http://www.andymark.com/RS775-p/am-2766.htm
http://www.andymark.com/product-p/am-2765.htm
That is Frank’s answer from the FRC Blog post on motor controllers regarding the legality of 2016 motors.