Synthetic fluid transmission flush

[sean99]

I have 126,000 miles and just swiched to the Mobil 1 synthetic motor oil with Mobil 1 filter.I would like to go synthetic throughout.I have 83k on the trans. and 30k on the valve body and filter.
Should I replace the filter or can I get away with just the flush?
How long can I go or should I go once switched over on both motor and trans before changing again? miles/time?
The rear end has 25k on it with Puratech gear oil GL5 and sta-lube additive.Should this be changed also?

1999 E.B. 4.0 sohc 4X4
Thanks,Sean

 

[Glacier991]

I moved this to the transmissions forum, as I think you will get a better response. Aldive will be all over this like stink on a skink!