Inner sleeves for all solo LPs show the covers of all 4 solo LPs.
There ARE solo LPs with different printing on the labels, so there may have been several Casablanca pressings.
The Mercury/Polygram pressing is easy to spot, as it has the UPC symbol on the back of the album.
Inserts: (1st pressing only) Each solo LP contained an illustrated poster of the KISS member whose album it was, and the 4 posters fit together to form one giant poster. Also each solo LP has a different merchandise oreder form (Paul Stanley´s having Paul merchandise, etc), and Peter Crss´s album also contained a paper sheet with information about his album.
(Taken from the book: "KISS Collectibles Identification & Price Guide" - 1993, Karen & John Lesniewski)