poss. gmc streetcoupe

[gmc street coupe]

hello everyone, I have a truck that im trying to get some info. as to if its rare. Its a 73 gmc 2wd stepside, the truck is all orig. It has a 454,12 bolt rear with 4:11 posi. It has the serria grand package,factory tach,tilt steering and the bench seat with the fold down console

Im am aware of the gmc street coupes and the chev sport coupes and who rare these are but that was not offered until 1976. My truck is exactly what a street coupe would be but its a 73. Does any one have any info about this? It also has a metal plate on the doorjam with some info and it sayes gmc motor coach custom divison
any help would be great