As per title really. The replacement part for my XJR6 is a fibre gasket, whereas the original was plastic and had a rubber bead around it. Has anyone had similar woes and how did they fix it?
Are the original gaskets available still?

 

I ran into this issue when I first got my XJR. There are two versions of the transmission and you need to get the Jaguar specific 4L80E gasket. The more common 4L80E gasket used on Chevy's aren't exactly the same.

This was the thread I posted about the same issue a few years back

https://www.jaguarforums.com/forum/x...rchase-119923/

 

You don't necessarily need to replace the gasket. I did an oil and filter change and thought I would need a new trans sump gasket. I bought two gaskets, the first was the wrong shape because the Jag version of the 4L80e has a slightly different case to the GM version, and the second was the right shape but was obviously of inferior quality to the original so I chose not to use it.
The original gasket as you mentioned has a rubber O-ring-like seal right around it and the bolt holes have steel inserts. My old one looked ok so I reused it and it does not leak at all.
Be careful that the bolt hole threads and bolts are clean and don't overtighten the bolts as the case thread will easily strip, and then it probably will leak.
By the way, what colour is your trans dipstick handle (mine is red)?

 

Thanks guys. I actually bought the gasket from Jaguar classic parts here in UK. It's the right one, just not as good as the one with the rubber seal/ o-ring. I wonder if trying to track down a second hand one might be the way to go?