Yes there is a flange gasket where the stock down pipe joins the collector.
The 97+ rivs have a slightly different style than the 95/96 rivs but the location is pretty much the same.
What make you think that is where the leak is from? It is much more likely that your manifolds have cracks around the primaries than a leaking stock gasket IMO.
One way to find out is to seafoam the car (brake booster line) and watch where the smoke comes from.
1996 with 254k miles, L32 4" FWI -> ported N* -> Ported Gen V w/3.0" Pulley, Stage 3 Phenolic I/C, ZZP FMHE, 1.84 RR, Headers and 3" pipe to mufflers, F-body brakes, and lowered on Eibachs. -RIP
AMG C400 White on black -daily