Sorry, vvpete,I've never seen an M47 with an oil filter .
Those metal shavings/paticles need to come out , and changing the trans oil is the only way on our Volvos.
Therefore, IMO, an M47 trans will benefit from changing it's oil periodically.
I'm using Royal Purple Synchro Max trans syn oil in mine. It is working well in mine.
But I'm using it because when I changed it I couldn't find the OEM Volvo M47 trans oil readily, for a good price. I'm running @ 2.2-2.5 qts in my M47. This required jacking the front of the car up pretty high to be able to pour it all in .
And I agree that the OEM M47 Syn oil is best to use if one can get it,in an M47, & using ATF type F in a M46 is probably best especially for the $ spent, (due to hydraulic operation of the Laycock OD unit)and they also benefit from frequent ATF type F trans oil changes as well. But many are doing well with Redline syn in M46s it seems.
And while we're at it, changing the diff oil periodically is a damn good idea too. I'm using Royal Purple diff oil at the moment too.