I'm going to guess it's from an 8V A2 with the clip-on single downpipe. Most likely one of the 85HP GX engines with CIS injection (1985-1987). Later RV engines (Digifant injection, late 1987 and up) may or may not have had this manifold (for example, my '91 GTI (California specification) had a single outlet manifold but it was a bolt-on style for the downpipe connection but I'm not sure if all RV engine codes had the bolt-on connection like mine did).