Back when parts countermen still had catalogs,they could look up shocks in "the back pages" by extended & retracted lengths,and the mounting codes for both ends..not sure if that is still possible with computer listings..
To get the shocks you want you'll have to measure how long they need to be extended fully,and compressed fully,and then the right mounting code for each end --and look for ones that meet those specs..
I was able to find some air shocks for the front of a plow truck I had that way ,but that ended up not being a good solution for the sagging springs..I also found shocks that were longer than the originals on my '69 GTO ,they were topping out after I installed a coil spring spacer lift kit to fit larger tires on it..