Upper control arms.
 

Working on a new to me 1979 l82. Rebuilding the front end with a kit from a corvette vendor. Upon removal of the upper control arms, the drivers side is 11-1/8”. The pass side is 10-3/4 from bushing mount to bushing mount. Shouldn’t they be the same measurement? Just curious.

sounds like someone damaged the arm when doing a bushing removal or install

Can you use a small "bottle jack" to spread apart the damaged arm?

That will probably work....BUT....IIRC, the bolts that hold the a-arm to the shaft, pretty much "bottom out" in the shaft, which holds the arm in place. If the one arm has been "crushed" by 3/8", I'd be inclined to first verify that the shaft is the correct one for the car.

New tubular a arms ordered!

Good idea...do they come with the cross shafts installed?