see, I dunno
I have a big blue point impact gun and a blue point air ratchet...
I only ever use the air ratchet on body panels/door work...it isnt good for much else
and the impact only gets used for wheels and suspension parts (I have torque sticks so you never under or over torque wheels)...again its a big impact.
honestly on a transmission or engine, Id only use a breaker bar (btw a little propane torch can be enuff to heat up a fussy nut to break it loose no need for "hot wrenches"aka full size torches) and regular ratchets....tight spots Ive been known to break a ratcheting wrench...or four
I def use my wobble sockets and various universal joints + extensions more then anything. My wobbles are also my most borrowed tools.
BUT if your intent on air toys...Id get the impact, but Id go for a big impact, you'll burn up one of those little caftsman butterflys quick.
also....find out if it needs air tool oil...some of the newer homeowner stuff doesnt, but the oiled stuff holds up longer