You're brother-in-law made out like a bandit !
Just read this post after replying to the other post. A Q-jet means it's an 85 or newer engine, as thermoquads ended in after 84.
Yes that is fulltime 4WD, the only way to disengage it, is to pull the front driveshaft (good for 2-4mpg better).
Get him to spend $30 and get the remote trans oil filter kit from Summit. That and half an hour will help him get more miles out of his 727.
Don't understand the hate you've got for 727s, though I'll join you on ranting about the lighter duty 904s. You gotta understand these trannies lived and survived behind real 490 ft/lb of torque Hemis and 440 Six packs.
There was a time in the early 70s when many GM drag racers were putting 727s behind their rat motors with adaptor plates.
That bark of the tires you like is a trademark signature of the Torqueflite. They shift pretty hard stock and can be modified, with next to no aftermarket parts, to crucify tires, U-joints and lug nut studs.
You can dial up the line pressure (free), pitch the accumulator spring(free) and adjust the kickdown linkage (free) to make a 727 shift like your being rear ended.