I am due for a timing belt. While shopping on FCP Groton, they make a distinction between engine serial # 1266127 using one TB kit and post SN #1266127 using another. I looked in my engine and found the sticker on the plastic TB cover had faded. I went ahead and ordered the kit for newer engines (with water pump), but now I'm wondering what the difference is and if it's the wrong kit do I just need some additional parts or is the whole kit useless. I see they sell a spacer or washer for one of the pulleys, but that can't account for the price difference.

And BTW who at Volvo thought it was a good idea to identify the engine SN by a sticker on a plastic part that can fade due to heat and age not to mention peeling?