Are you breathing pure Oxygen through your mask or what “CF” ? This is all bollox about chassis being supplied by GUY Motors with a.n. other engine then exchanged for an 8LXB ! absolute bollox honestly ! I have never said that there had NEVER been an 8LXB BIG J but there would never have been anymore than a handful and only then with a bit of “arm twisting” by large BIG J operators e.g. SOM . GUY’s are what became known as the “Cinderella poverty spec builder” within the Leyland Group so the possibility of them obtaining supplies of the , what was at the time, the premier heavy commercial engine in the UK i.e. The 8 LXB were practically zero ! Incidentally the 180LXB only became available in quantity after it was down rated from powering 32 ton gvw chassis to 30:5 gvw. then Guy and Seddon manufactured with the 180LXB were in plentiful supply and , of course , they were still Kosher 20 tonners ! I know 'cause I ran plenty ! 
PS ask Matron to alter the mixture by adding a bit of “laughing gas” to the Oxygen then maybe your posts may improve dramatically in their quality 
Stay Safe Mate ! Bewick.