4.2 and 5.0 litre V8 transmission mount pattern
 

I'm struggling to find a definitive answer on this - do the 4.2 and 5.0 V8s have the same bell housing / transmission bolt patterns?

I know the 4.2 and earlier V8s are the same as the 2.7 diesel, and believe the 5.0 V8 is the same as the 3.0 V6 but are they all the same as each other?

Thanks

No they are totally different

Cambo, would it be possible to get the bell housing from one engine and bolt it on to a different tranny. This is why I say this and maybe where the original poster is taking this is that if you take the newer XJs, they all use the 8 speed tranny which I believe is the same in every vehicle, regardless of the motor. The only thing that differs is the bell housing on the front of the tranny. This should allow you to take a given tranny and once you change the bell housing, bolt it on to a different engine. Now, exactly what will bolt up to what at that point, that gets a lot more involved.

I know there are shops out there that will find a bell housing and adapt it to allow you to make up your own custom engine/tranny setup. But, I am sure that this comes at a pretty penny.

The bellhousing on the ZF 6HP and 8HP is not removable, it is one with the transmission housing in a single casting.

So you can't take a 5.0L 6HP and bolt it up to a 4.2L 6HP, for example.

The 8HP is NOT the same in every vehicle, there are dozens of variants with different internals and bellhousings to suit different engines.