timing chain guides...
 

dont shoot me, i searched. when i look up the chain guides, i get two diffrent part numbers depending on if it is built before or after 8-01.

before 8-01 it shows a guide covered in a grey plastic. after 8-01 they are aluminum with a red plastic for the chain to slide on.

i guess my question is, can i use the later aluminum ones on the erlier engine???

they also show diffrent chains for the same date ranges. does anyone know the diffrences...

Jaguar changed from full plastic bodied tensioners in August '01 to metal ones. By all means use the metal ones. That is the purpose of Jaguar's and your upgrade. The chains changed in February '02 and are not interchangeable with the earlier ones.

Be sure to replace the longer bolts used with the plastic tensioners with the shorter ones for the metal ones.

Try the FAQ sticky on the XK8/R forum for more information than you ever wanted.

You don't say when your engine was built and that is important. My '01 XJ8L engine build date is 8.24.00 and it took the "newer" primary guides you seem to be describing just fine, but you need to be sure about which chains you have. The dealer can tell you exactly when your engine was built from the VIN, which is more important than the model year or vehicle assembly date in these engine issues, especially when you are close to these transition points.

My old primary guides "looked" much different than the new replacements. Especially all the cracks!

my engine wasbuilt 10/17/00, so it deffinatly did not come with updated parts

Sorry to butt in, but I believe WmTerry's original query was regarding lower chain guides, not upper chain tensioners....

The later aluminum-and-red-plastic guides are NOT interchangeable with the early grey-plastic ones. Nor are the chains.
(BTW, if you need some, they are much cheaper at the Ford dealer, Lincolns & Aston Martins only ever used the upgraded ones)

yep that was exactly it...thanks