The 82A cab continued to be used until May 1930.
One difference is the gas tank, which remained in the 1928-29 "curve" and hood but the fill pipe was changed to the 1930 quarter turn type.
For the AA truck after about October '29 the rest of the truck stayed basically 1928-29, but with a frame/suspension used in the later 4 speed truck. One assumes that the same body modus was followed on the A truck in 3 speed. As in only with the upgrade to the rounded corner cab after May did the fenders/hood follow.
Now timing around that change over period was a little "dicey." To my knowledge there is no "mix & match" of body parts between 28-29 and 30-31. But with up to a six week "float" between engine numbers and assembly to a chassis, it is very possible that six weeks either side of a late May change over might be the other type.
But - no mix & match beyond the gas tank filler.
My March '29 truck (Avatar) was assembled at the Somerville, MA Assembly Plant - probably came as a chassis to which they applied the body parts. It appears to have been very much a "lets make something we can sell" effort with black painted gearshift and instrument panel - both of which showed nickel "defective" under the paint.
Joe K