I have a 2002 National RV Tradewinds Model 390 with Cat 330 engine and the GM Allison 3060 transmission. I just had the first tranny oil and filter change done at about 10,000 miles...after the oil change, the tranny downshifted really hard going from 5th to 4th. Have driven it for about 100 miles since then on a test drive and still shifting hard only at that particular downshift...doesn't matter whether I am in "economy" mode or not...same downshift. Dealer in FL where I had service work done, changed the oil and filters a second time and used DEXRON III oil from the quart containers instead of from a bulk container. It seems to be a little better but not as smooth as originally. I also experience really harsh downshift when I use the exhaust brake and I believe from all I can tell it downshifts into 4th or 3rd gear when using the exhaust brake. Any thoughts or comments would be appreciated. I am heading for near Inpls, IN in about 3 wks and am wondering if I should find a GM Allison service shop there to have them take a look or not. Thanks in advance for any info you might be able to offer to me.