I swear, everytime I change the tranny fluid in my Silverado I swear I'm not going to go through the hassle of replacing that small seal that goes inside the transmission (into which the transmission filter neck fits). That thing is the biggest PIA to get out. This past time I marred the soft transmission metal trying to get that seal out. Next time I think I'm going to just leave it in. I can't think why I couldn't just swap out the filter, that rubber seams pretty robust.