71, 198 slant choke

Picture certainly helps. It's to bad we don't have the casting number from your exhaust manifold Unfortunately it's difficult to see when the manifold is bolted to the engine. From what's visible in the photo you appear to have the older style manifold. Vaguely remember the small bolt you're asking about but don't know the size. Is there a cup and gasket under your choke as seen here. Dodge 225 Slant 6 Dodge Plymouth Choke Thermostat well cup 2946529 | eBay