Do You have a link to the video with Glen playing Bodies? I can't find one which dates from the 70's, and I'm surprised to hear that there's an "official" one of an album track which would never have got any airplay, due to subject matter and language.I saw him playing don't see why he would play it if he didn't write it unless Sid rewrote the bass line for the album hard to say with Malcom running things though
Edit
I know matlocks basslines were more complex
As for Sid "rewriting the bass line", the bass on the record is Steve Jones.