904 tranny

340's only came with 727's. After all these years, there are a lot of things that may not be original, including the engine! 904's are great little transmissions. But they all need at least a good shift kit to help them live if you run them hard. But there is no way to know what kind of shape everything is in, especially if even the current owner doesn't know. Take it for a drive and hope you can determine how well it works then.

Make sure if it's a 340 and not a disguised 318. Check the VIN to see if it's an original 340 or 318 Duster.

If it's an 8 3/4" rear in it, then that has been swapped in also. '72 was the last year of 8 3/4's in A-bodies. Biggest they got was an 8 1/4" rear.

Check bolt patterns. The 8 3/4 may have the OEM 4" bolt pattern. If front brakes are disc, it should be 4.5" up there. I believe drums up front would be 4".