The existing sewer spigot for your RV is likely attached with ABS cement, so the only way to remove it will be to simply cut it it off after taking out the mounting screws. If you have a 2 inch pipe then the Valterra RV Sewer Spigot # T1006-2 that you mentioned is the correct part. If you need 1-1/2 inch spigot you will use # T1006-1 instead.
We do also have ABS Solvent Cement with part # A05-0303 that you can use when installing the new part. view full answer...