I have a Model 18-3 that dates to 1971. It has the Target Trigger and Target Hammer but unnumbered Magna Stocks. I bought it used and have not lettered it but have always thought it odd to only have 2 of the 3 target options. While I have seen many Model 19's with 4" barrels and the 3T options I don't recall seeing many Model 15's or Model 18's with target options.