Need a V-8 K-frame for a 1973 Swinger

So I looked at my torsion bars today and they read "891L" and "890R" denoting L as coming from the drivers side. It's a 1973 and I know it was a /6 car due to the 7 1/4" rear... Any ideas as to why I would have stock 383 bars? Also, anybody know how to tell a 1973 /6 k-frame from a v8 k-frame? I'd hate to buy one if I already have one.