Foxeye prob different then, i remember having my tank off & the filter going in from the top down, i doubt i could have managed it with the tank still on...well maybe with it propped up but i would no doubt keep knocking it off its prop & making a mess, tank off gave me more room.
Forgot i didnt do any proper rad flush...but i did fire the garden hose down the filler spout on full blast until the water coming out the drain hole ran clear..which in my case didnt take long.