The sealant I used on my 06 Itasca is Manus 75AM bright white (I have a white roof & gutter). It's Winnebago p/n 072889-10-000. The sealant is urethane based, not silicone. I dug out all the old sealant and scrubbed deep down into the J-channel. As a final step before sealing, I scrubbed the area with acetone. If you have body paint, Winnebago recommends p/n 094401-04-000. It's a clear urethane called Stone Mason Gutter and Siding Sealant, made by the Henry Company.
Fran, Mary & Zoey (silver Cocker)
2006 Itasca Sunrise 35A, 2005 W-22, Allison 1000 5 speed
'13 Ford Focus ST or '10 Prius on Master Tow Dolly 80THD-SB or '00 Jeep Cherokee 4-down