B vs RB

I've read about the difference and I think got good understanding, but I had 1966 belevdere 2 with g code commando 383 with 4 barrel carter carb. 1966 IMO was confusing year for 383. IMO the only way to tell would be verify the stroke. 3.338 B, and 3.75 RB. I also think any 383 before 66 would be B series. IMO any after 67 would be RB due to 440 come out in 66 and was created from the RB block. IMO all 383s after 67 were RBs, but I have found no way of knowing that. I do know all Road Runners and Super Bee engines were RB high preformance 383s with 3. 75 stokes. I do know all 361s 1966 (look just like 383s) were two barrel engines. Does that mean all two barrel 383s were actually 361?

I find it really confusing to tell 1966 383 was B or RB block without verification of the stroke?

Anybody else know any other differences, like castings on the block that would fornsure identify RB 383?