So what's the deal? Which carb is the right one?

townsend said
The 3870902 Holley carb was used on 75-77 dodge vans with 225 engine and automatic transmission.
3830402 is the correct carb for your 1974 duster with 225 engine.

Thanks, townsend. Do you have the model number of the 3870902 Holley 1945 carb?