Any Pardner shotgun action made 1987 and later IS an SB1 except a 10ga, if you mean the SB1 rifle frame, the only difference is the factory SB1 rifle frames usually have smaller rifle type firing pins and a smaller hole in the standing breech for same, but they fit 357 and 44 mag accessory barrels to any SB1 shotgun frame made 1987 and later.
Tim