Outer Limits 4x4 Board

I bought a h20a with 4 speed auto not long ago

Now i was told when i bought it that it had upgraded bands (what does this mean?) or somethng like that done to it, it shifts firmly and doesn't slip or have any other problems

Now the problem when cruising along at about 90-100kph in overdrive and come to an incline or accelerate enough for it to kick back from over drive it makes a rattling noise (sounds kind of like an exhaust heat shield rattle)
and lasts for all of 2 seconds max. Like i said other than this noise the gearbox is great.

does anyone have any idea what it could be?

secondly Last night i went for a bit of a mud run, while trying to get up muddy clay hills etc reving the car once id back off the engine would stall while still in drive

then i noticed that it wont start in neutral only park could these problems be linked to this funny noise?

it also has no problem starting after stalling

thanks inbits

Had same problem with rattling noise. Heard it while accelerating. Disappeared after removing inside of catalityc converter, it was just bouncing piece of junk .