There are 2 versions, 73-80 plain and 77-80 scripted (Chevrolet or GMC). The scripted are for 77-80 trucks, but can be modified for the 73-76 versions. They haven't send me detailed pictures or info on what exactly needs to be "modified" as factory one should be able to be swapped relatively easy.
The cost on the plain is $200, cost for the scripted Chevy is $325, (GMC= 349) Shipping to you should be about $45. Scripted are GM licensed