Suburban and truck Frame

[pontgta]

Would like to know if the truck 73-87 frame and 73-91 suburban frames are the same. I went to the local pick and pull, and saw a hidden hitch but did not know if it would fit.
Also , would like to know if the "valley/crossmember"( i do not know what its called.) where the motor mounts to the frame. Are all those components the same along with all the steering components?... Basically i think there are a few bolts that attach this "valley/crossmember" to the frame and then the everything attached to the wheels comes off the truck... I have been going to a few junks yards lately and see all kinds of parts.