the 300 was the last car to have hard copy manuals produced, these are rare and hard to find now, JH then took these hard copies along with all the previous models and transferred all the info onto the the discs you can buy via JH
at the same time JH and Classic parts became responsible for all historical data and parts supply of cars up to the 300, only recently 300 (within the last 2 years) has been included into the JH and Clasic parts supply chain
the 308 stuff has not been handed over from Jaguar to JH or Classic parts yet, hence if you search a common 300/308 part on the Classic Parts website it will show as contact us even though we all know it available
There were no hard copy manuals at all for 308, but you may well find a JTIS disc on ebay which will give you some info, but all of these cars were scanned for faults on IDS at the dealers, no traditional manuals were held. There may well be some training manuals available, I have a 350 one which came from Jaguar and I know there are a few S Type items copied, which Mike Kennedy has on file
this link as pointed to by SV8predator in another thread also looks good
http://jaguar.telko.ru/XJ8%201999.pdf
not what you want to hear I know, but fact I am afarid, this is where the value of BB's such as on here can be of huge help, the knwoledge held JEC members is immense, ask your questions and and answer will be forthcoming I'm sure