I do not know the older campers but the newer ones are pretty bullet proof on siding interlock leaks. The leaks generally come from any hole in the siding. Window, clearance light, etc.
However that is not to say that something shifted and the interlocking siding is not overlapping well.
What else is in the area you are seeing the leak, any chance of some pics so we can see what you are up against? The leak may be a ways down/up the line and wicking down the siding.
Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC
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